Bug 261037. Support scrolled fieldsets. r=mats

The main change here is to have nsCSSFrameConstructor able to construct
a scrollframe for nsFieldSetFrame's inner frame.
To make this work properly (as much like normal scrolled elements, and
to be consistent with Chrome), we need another major change, which is to move
the padding from the nsFieldSetFrame to its inner frame. We do this by copying
the padding to the inner frame and ignoring the padding on the outer frame.
To get this right for percentage padding and intrinsic widths is a little
tricky. For that, we need nsLayoutUtils::IntrinsicForContainer to be able to
ignore the padding on a frame so we don't add it twice.
Overriding nsFieldSetFrame::GetScrollTargetFrame makes setting scrollTop/
scrollLeft on a <fieldset> work as expected.
* * *
Bug 261037 - A fieldset overflow:auto reftest.

--HG--
extra : rebase_source : 6ca585f685965d3a538bde64ad4057c5fd7b538f

content/base/src/Element.cpp

@@ -502,8 +502,8 @@ Element::GetScrollFrame(nsIFrame **aStyledFrame, bool aFlushLayout)
 
   // menu frames implement GetScrollTargetFrame but we don't want
   // to use it here.  Similar for comboboxes.
-  if (frame->GetType() != nsGkAtoms::menuFrame &&
-      frame->GetType() != nsGkAtoms::comboboxControlFrame) {
+  nsIAtom* type = frame->GetType();
+  if (type != nsGkAtoms::menuFrame && type != nsGkAtoms::comboboxControlFrame) {
     nsIScrollableFrame *scrollFrame = frame->GetScrollTargetFrame();
     if (scrollFrame)
       return scrollFrame;

layout/base/nsCSSFrameConstructor.cpp

@@ -3050,39 +3050,51 @@ nsCSSFrameConstructor::ConstructFieldSetFrame(nsFrameConstructorState& aState,
   nsIContent* const content = aItem.mContent;
   nsStyleContext* const styleContext = aItem.mStyleContext;
 
-  nsIFrame* newFrame = NS_NewFieldSetFrame(mPresShell, styleContext);
+  nsIFrame* fieldsetFrame = NS_NewFieldSetFrame(mPresShell, styleContext);
 
   // Initialize it
   InitAndRestoreFrame(aState, content,
                       aState.GetGeometricParent(aStyleDisplay, aParentFrame),
-                      newFrame);
+                      fieldsetFrame);
 
   // Resolve style and initialize the frame
   nsRefPtr<nsStyleContext> fieldsetContentStyle;
   fieldsetContentStyle = mPresShell->StyleSet()->
     ResolveAnonymousBoxStyle(nsCSSAnonBoxes::fieldsetContent, styleContext);
 
+  const nsStyleDisplay* fieldsetContentDisplay = fieldsetContentStyle->StyleDisplay();
+  bool isScrollable = fieldsetContentDisplay->IsScrollableOverflow();
+  nsIFrame* scrollFrame = nullptr;
+  if (isScrollable) {
+    fieldsetContentStyle =
+      BeginBuildingScrollFrame(aState, content, fieldsetContentStyle,
+                               aState.GetGeometricParent(fieldsetContentDisplay, fieldsetFrame),
+                               nsCSSAnonBoxes::scrolledContent,
+                               false, scrollFrame);
+  }
+
   nsIFrame* blockFrame = NS_NewBlockFrame(mPresShell, fieldsetContentStyle,
                                           NS_BLOCK_FLOAT_MGR |
                                           NS_BLOCK_MARGIN_ROOT);
-  InitAndRestoreFrame(aState, content, newFrame, blockFrame);
+  InitAndRestoreFrame(aState, content,
+    scrollFrame ? scrollFrame : fieldsetFrame, blockFrame);
 
-  aState.AddChild(newFrame, aFrameItems, content, styleContext, aParentFrame);
+  aState.AddChild(fieldsetFrame, aFrameItems, content, styleContext, aParentFrame);
   
   // Process children
   nsFrameConstructorSaveState absoluteSaveState;
   nsFrameItems                childItems;
 
-  newFrame->AddStateBits(NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
-  if (newFrame->IsPositioned()) {
-    aState.PushAbsoluteContainingBlock(newFrame, newFrame, absoluteSaveState);
+  blockFrame->AddStateBits(NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
+  if (fieldsetFrame->IsPositioned()) {
+    aState.PushAbsoluteContainingBlock(blockFrame, fieldsetFrame, absoluteSaveState);
   }
 
   ProcessChildren(aState, content, styleContext, blockFrame, true,
                   childItems, true, aItem.mPendingBinding);
 
   nsFrameItems fieldsetKids;
-  fieldsetKids.AddChild(blockFrame);
+  fieldsetKids.AddChild(scrollFrame ? scrollFrame : blockFrame);
 
   for (nsFrameList::Enumerator e(childItems); !e.AtEnd(); e.Next()) {
     nsIFrame* child = e.get();
@@ -3094,21 +3106,25 @@ nsCSSFrameConstructor::ConstructFieldSetFrame(nsFrameConstructorState& aState,
       // GetAdjustedParentFrame() below depends on this frame order.
       childItems.RemoveFrame(child);
       // Make sure to reparent the legend so it has the fieldset as the parent.
-      fieldsetKids.InsertFrame(newFrame, nullptr, child);
+      fieldsetKids.InsertFrame(fieldsetFrame, nullptr, child);
       break;
     }
   }
 
+  if (isScrollable) {
+    FinishBuildingScrollFrame(scrollFrame, blockFrame);
+  }
+
   // Set the inner frame's initial child lists
   blockFrame->SetInitialChildList(kPrincipalList, childItems);
 
   // Set the outer frame's initial child list
-  newFrame->SetInitialChildList(kPrincipalList, fieldsetKids);
+  fieldsetFrame->SetInitialChildList(kPrincipalList, fieldsetKids);
 
-  newFrame->AddStateBits(NS_FRAME_MAY_HAVE_GENERATED_CONTENT);
+  fieldsetFrame->AddStateBits(NS_FRAME_MAY_HAVE_GENERATED_CONTENT);
 
   // Our new frame returned is the outer frame, which is the fieldset frame.
-  return newFrame; 
+  return fieldsetFrame; 
 }
 
 static nsIFrame*
@@ -3262,6 +3278,17 @@ nsCSSFrameConstructor::FindDataByTag(nsIAtom* aTag,
 #define COMPLEX_TAG_CREATE(_tag, _func)             \
   { &nsGkAtoms::_tag, FULL_CTOR_FCDATA(0, _func) }
 
+static bool
+IsFrameForFieldSet(nsIFrame* aFrame, nsIAtom* aFrameType)
+{
+  nsIAtom* pseudo = aFrame->StyleContext()->GetPseudo();
+  if (pseudo == nsCSSAnonBoxes::fieldsetContent ||
+      pseudo == nsCSSAnonBoxes::scrolledContent) {
+    return IsFrameForFieldSet(aFrame->GetParent(), aFrame->GetParent()->GetType());
+  }
+  return aFrameType == nsGkAtoms::fieldSetFrame;
+}
+
 /* static */
 const nsCSSFrameConstructor::FrameConstructionData*
 nsCSSFrameConstructor::FindHTMLData(Element* aElement,
@@ -3284,9 +3311,7 @@ nsCSSFrameConstructor::FindHTMLData(Element* aElement,
                "Unexpected parent for fieldset content anon box");
   if (aTag == nsGkAtoms::legend &&
       (!aParentFrame ||
-       (aParentFrame->GetType() != nsGkAtoms::fieldSetFrame &&
-        aParentFrame->StyleContext()->GetPseudo() !=
-          nsCSSAnonBoxes::fieldsetContent) ||
+       !IsFrameForFieldSet(aParentFrame, aParentFrame->GetType()) ||
        !aElement->GetParent() ||
        !aElement->GetParent()->IsHTML(nsGkAtoms::fieldset) ||
        aStyleContext->StyleDisplay()->IsFloatingStyle() ||
@@ -5984,9 +6009,7 @@ nsCSSFrameConstructor::IsValidSibling(nsIFrame*              aSibling,
 
     return true;
   }
-  else if (nsGkAtoms::fieldSetFrame == parentType ||
-           (nsGkAtoms::fieldSetFrame == grandparentType &&
-            nsGkAtoms::blockFrame == parentType)) {
+  else if (IsFrameForFieldSet(parentFrame, parentType)) {
     // Legends can be sibling of legends but not of other content in the fieldset
     nsIAtom* sibType = aSibling->GetContentInsertionFrame()->GetType();
     bool legendContent = aContent->IsHTML(nsGkAtoms::legend);
@@ -7083,7 +7106,7 @@ nsCSSFrameConstructor::ContentRangeInserted(nsIContent*            aContainer,
   // fieldsets have multiple insertion points.
   NS_ASSERTION(isSingleInsert || frameType != nsGkAtoms::fieldSetFrame,
                "Unexpected parent");
-  if (frameType == nsGkAtoms::fieldSetFrame &&
+  if (IsFrameForFieldSet(parentFrame, frameType) &&
       aStartChild->Tag() == nsGkAtoms::legend) {
     // Just reframe the parent, since figuring out whether this
     // should be the new legend and then handling it is too complex.

layout/base/nsLayoutUtils.cpp

@@ -2807,7 +2807,8 @@ static int32_t gNoiseIndent = 0;
 /* static */ nscoord
 nsLayoutUtils::IntrinsicForContainer(nsRenderingContext *aRenderingContext,
                                      nsIFrame *aFrame,
-                                     IntrinsicWidthType aType)
+                                     IntrinsicWidthType aType,
+                                     uint32_t aFlags)
 {
   NS_PRECONDITION(aFrame, "null frame");
   NS_PRECONDITION(aType == MIN_WIDTH || aType == PREF_WIDTH, "bad type");
@@ -2901,15 +2902,17 @@ nsLayoutUtils::IntrinsicForContainer(nsRenderingContext *aRenderingContext,
           // fall through
         }
         case NS_STYLE_BOX_SIZING_PADDING: {
-          const nsStylePadding* stylePadding = aFrame->StylePadding();
-          nscoord pad;
-          if (GetAbsoluteCoord(stylePadding->mPadding.GetTop(), pad) ||
-              GetPercentHeight(stylePadding->mPadding.GetTop(), aFrame, pad)) {
-            heightTakenByBoxSizing += pad;
-          }
-          if (GetAbsoluteCoord(stylePadding->mPadding.GetBottom(), pad) ||
-              GetPercentHeight(stylePadding->mPadding.GetBottom(), aFrame, pad)) {
-            heightTakenByBoxSizing += pad;
+          if (!(aFlags & IGNORE_PADDING)) {
+            const nsStylePadding* stylePadding = aFrame->StylePadding();
+            nscoord pad;
+            if (GetAbsoluteCoord(stylePadding->mPadding.GetTop(), pad) ||
+                GetPercentHeight(stylePadding->mPadding.GetTop(), aFrame, pad)) {
+              heightTakenByBoxSizing += pad;
+            }
+            if (GetAbsoluteCoord(stylePadding->mPadding.GetBottom(), pad) ||
+                GetPercentHeight(stylePadding->mPadding.GetBottom(), aFrame, pad)) {
+              heightTakenByBoxSizing += pad;
+            }
           }
           // fall through
         }
@@ -2960,18 +2963,22 @@ nsLayoutUtils::IntrinsicForContainer(nsRenderingContext *aRenderingContext,
   // percentages do not operate linearly.
   // Doing this is ok because although percentages aren't handled
   // linearly, they are handled monotonically.
-  nscoord coordOutsideWidth = offsets.hPadding;
-  float pctOutsideWidth = offsets.hPctPadding;
-
+  nscoord coordOutsideWidth = 0;
+  float pctOutsideWidth = 0;
   float pctTotal = 0.0f;
 
-  if (boxSizing == NS_STYLE_BOX_SIZING_PADDING) {
-    min += coordOutsideWidth;
-    result = NSCoordSaturatingAdd(result, coordOutsideWidth);
-    pctTotal += pctOutsideWidth;
+  if (!(aFlags & IGNORE_PADDING)) {
+    coordOutsideWidth += offsets.hPadding;
+    pctOutsideWidth += offsets.hPctPadding;
 
-    coordOutsideWidth = 0;
-    pctOutsideWidth = 0.0f;
+    if (boxSizing == NS_STYLE_BOX_SIZING_PADDING) {
+      min += coordOutsideWidth;
+      result = NSCoordSaturatingAdd(result, coordOutsideWidth);
+      pctTotal += pctOutsideWidth;
+
+      coordOutsideWidth = 0;
+      pctOutsideWidth = 0.0f;
+    }
   }
 
   coordOutsideWidth += offsets.hBorder;

layout/base/nsLayoutUtils.h

@@ -988,9 +988,13 @@ public:
    * and margin.
    */
   enum IntrinsicWidthType { MIN_WIDTH, PREF_WIDTH };
+  enum {
+    IGNORE_PADDING = 0x01
+  };
   static nscoord IntrinsicForContainer(nsRenderingContext* aRenderingContext,
                                        nsIFrame* aFrame,
-                                       IntrinsicWidthType aType);
+                                       IntrinsicWidthType aType,
+                                       uint32_t aFlags = 0);
 
   /*
    * Convert nsStyleCoord to nscoord when percentages depend on the

layout/forms/nsFieldSetFrame.cpp

@@ -15,6 +15,7 @@
 #include "nsStyleConsts.h"
 #include "nsDisplayList.h"
 #include "nsRenderingContext.h"
+#include "nsIScrollableFrame.h"
 #include "mozilla/Likely.h"
 
 using namespace mozilla;
@@ -78,6 +79,10 @@ public:
     return nsContainerFrame::IsFrameOfType(aFlags &
              ~nsIFrame::eCanContainOverflowContainers);
   }
+  virtual nsIScrollableFrame* GetScrollTargetFrame() MOZ_OVERRIDE
+  {
+    return do_QueryFrame(GetInner());
+  }
 
 #ifdef ACCESSIBILITY  
   virtual mozilla::a11y::AccType AccessibleType() MOZ_OVERRIDE;
@@ -356,10 +361,14 @@ nsFieldSetFrame::GetIntrinsicWidth(nsRenderingContext* aRenderingContext,
   }
 
   if (nsIFrame* inner = GetInner()) {
+    // Ignore padding on the inner, since the padding will be applied to the
+    // outer instead, and the padding computed for the inner is wrong
+    // for percentage padding.
     contentWidth =
-      nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner, aType);
+      nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner, aType,
+                                           nsLayoutUtils::IGNORE_PADDING);
   }
-      
+
   return std::max(legendWidth, contentWidth);
 }
 
@@ -444,7 +453,10 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
 
   // We don't allow fieldsets to break vertically. If we did, we'd
   // need logic here to push and pull overflow frames.
-  nsSize availSize(aReflowState.ComputedWidth(), NS_UNCONSTRAINEDSIZE);
+  // Since we're not applying our padding in this frame, we need to add it here
+  // to compute the available width for our children.
+  nsSize availSize(aReflowState.ComputedWidth() + aReflowState.mComputedPadding.LeftRight(),
+                   NS_UNCONSTRAINEDSIZE);
   NS_ASSERTION(!inner ||
       nsLayoutUtils::IntrinsicForContainer(aReflowState.rendContext,
                                            inner,
@@ -459,8 +471,7 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
                "Bogus availSize.width; should be bigger");
 
   // get our border and padding
-  const nsMargin &borderPadding = aReflowState.mComputedBorderPadding;
-  nsMargin border = borderPadding - aReflowState.mComputedPadding;  
+  nsMargin border = aReflowState.mComputedBorderPadding - aReflowState.mComputedPadding;
 
   // Figure out how big the legend is if there is one. 
   // get the legend's margin
@@ -481,7 +492,7 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
     legendMargin = legend->GetUsedMargin();
     mLegendRect.width  = legendDesiredSize.width + legendMargin.left + legendMargin.right;
     mLegendRect.height = legendDesiredSize.height + legendMargin.top + legendMargin.bottom;
-    mLegendRect.x = borderPadding.left;
+    mLegendRect.x = 0;
     mLegendRect.y = 0;
 
     nscoord oldSpace = mLegendSpace;
@@ -513,16 +524,22 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
   // reflow the content frame only if needed
   if (reflowInner) {
     nsHTMLReflowState kidReflowState(aPresContext, aReflowState, inner,
-                                     availSize);
+                                     availSize, -1, -1, nsHTMLReflowState::CALLER_WILL_INIT);
+    // Override computed padding, in case it's percentage padding
+    kidReflowState.Init(aPresContext, -1, -1, nullptr,
+                        &aReflowState.mComputedPadding);
     // Our child is "height:100%" but we actually want its height to be reduced
     // by the amount of content-height the legend is eating up, unless our
     // height is unconstrained (in which case the child's will be too).
     if (aReflowState.ComputedHeight() != NS_UNCONSTRAINEDSIZE) {
-      kidReflowState.SetComputedHeight(std::max(0, aReflowState.ComputedHeight() - mLegendSpace));
+      kidReflowState.SetComputedHeight(
+         std::max(0, aReflowState.ComputedHeight() - mLegendSpace));
     }
 
-    kidReflowState.mComputedMinHeight =
-      std::max(0, aReflowState.mComputedMinHeight - mLegendSpace);
+    if (aReflowState.mComputedMinHeight > 0) {
+      kidReflowState.mComputedMinHeight =
+        std::max(0, aReflowState.mComputedMinHeight - mLegendSpace);
+    }
 
     if (aReflowState.mComputedMaxHeight != NS_UNCONSTRAINEDSIZE) {
       kidReflowState.mComputedMaxHeight =
@@ -533,7 +550,7 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
     // Reflow the frame
     NS_ASSERTION(kidReflowState.mComputedMargin == nsMargin(0,0,0,0),
                  "Margins on anonymous fieldset child not supported!");
-    nsPoint pt(borderPadding.left, borderPadding.top + mLegendSpace);
+    nsPoint pt(border.left, border.top + mLegendSpace);
     ReflowChild(inner, aPresContext, kidDesiredSize, kidReflowState,
                 pt.x, pt.y, 0, aStatus);
 
@@ -542,37 +559,45 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
     NS_FRAME_TRACE_REFLOW_OUT("FieldSet::Reflow", aStatus);
   }
 
-  nsRect contentRect(0,0,0,0);
+  nsRect contentRect;
   if (inner) {
-    // We don't support margins on inner, so our "content rect" is just
-    // its rect.
+    // We don't support margins on inner, so our content rect is just the
+    // inner's border-box.
     contentRect = inner->GetRect();
   }
 
-  // use the computed width if the inner content does not fill it
-  if (aReflowState.ComputedWidth() > contentRect.width) {
-    contentRect.width = aReflowState.ComputedWidth();
+  // Our content rect must fill up the available width
+  if (availSize.width > contentRect.width) {
+    contentRect.width = availSize.width;
   }
 
   if (legend) {
-    // if the content rect is larger then the  legend we can align the legend
-    if (contentRect.width > mLegendRect.width) {
+    // the legend is postioned horizontally within the inner's content rect
+    // (so that padding on the fieldset affects the legend position).
+    nsRect innerContentRect = contentRect;
+    innerContentRect.Deflate(aReflowState.mComputedPadding);
+    // if the inner content rect is larger than the legend, we can align the legend
+    if (innerContentRect.width > mLegendRect.width) {
       int32_t align = static_cast<nsLegendFrame*>
         (legend->GetContentInsertionFrame())->GetAlign();
 
-      switch(align) {
+      switch (align) {
         case NS_STYLE_TEXT_ALIGN_RIGHT:
-          mLegendRect.x = contentRect.width - mLegendRect.width + borderPadding.left;
+          mLegendRect.x = innerContentRect.XMost() - mLegendRect.width;
           break;
         case NS_STYLE_TEXT_ALIGN_CENTER:
           // Note: rounding removed; there doesn't seem to be any need
-          mLegendRect.x = contentRect.width / 2 - mLegendRect.width / 2 + borderPadding.left;
+          mLegendRect.x = innerContentRect.width / 2 - mLegendRect.width / 2 + innerContentRect.x;
+          break;
+        default:
+          mLegendRect.x = innerContentRect.x;
           break;
       }
-  
     } else {
       // otherwise make place for the legend
-      contentRect.width = mLegendRect.width;
+      mLegendRect.x = innerContentRect.x;
+      innerContentRect.width = mLegendRect.width;
+      contentRect.width = mLegendRect.width + aReflowState.mComputedPadding.LeftRight();
     }
     // place the legend
     nsRect actualLegendRect(mLegendRect);
@@ -594,16 +619,16 @@ nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
   // Return our size and our result
   if (aReflowState.ComputedHeight() == NS_INTRINSICSIZE) {
     aDesiredSize.height = mLegendSpace + 
-                          borderPadding.TopBottom() +
-                          contentRect.height;
+                          border.TopBottom() +
+                          (inner ? inner->GetRect().height : 0);
   } else {
-    nscoord min = borderPadding.TopBottom() + mLegendRect.height;
+    nscoord min = border.TopBottom() + mLegendRect.height;
     aDesiredSize.height =
-      aReflowState.ComputedHeight() + borderPadding.TopBottom();
+      aReflowState.ComputedHeight() + aReflowState.mComputedBorderPadding.TopBottom();
     if (aDesiredSize.height < min)
       aDesiredSize.height = min;
   }
-  aDesiredSize.width = contentRect.width + borderPadding.LeftRight();
+  aDesiredSize.width = contentRect.width + border.LeftRight();
   aDesiredSize.SetOverflowAreasToDesiredBounds();
   if (legend)
     ConsiderChildOverflow(aDesiredSize.mOverflowAreas, legend);
@@ -681,9 +706,6 @@ nsFieldSetFrame::ReparentFrameList(const nsFrameList& aFrameList)
 nscoord
 nsFieldSetFrame::GetBaseline() const
 {
-  // We know inner is a block, so calling GetBaseline() on it will do
-  // the right thing (that being to return the baseline of the last line).
   nsIFrame* inner = GetInner();
-  NS_ASSERTION(nsLayoutUtils::GetAsBlock(inner), "Unexpected inner");
   return inner->GetPosition().y + inner->GetBaseline();
 }

layout/reftests/forms/fieldset/dynamic-legend-scroll-1-ref.html

@@ -0,0 +1,24 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<style>
+fieldset { 
+  background:pink;
+  overflow:hidden;
+  height:100px;
+}
+legend::after { content:"legend"; }
+p {
+  background:lime;
+  height:20px;
+}
+</style>
+</head>
+<body>
+<fieldset id="f1"><legend></legend><p></p></fieldset>
+<br>
+<fieldset id="f2"><legend></legend><p></p></fieldset>
+<br>
+<fieldset id="f3"><legend></legend></fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/dynamic-legend-scroll-1.html

@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<html class="reftest-wait">
+<head>
+<style>
+fieldset { 
+  background:pink;
+  overflow:hidden;
+  height:100px;
+}
+legend::after { content:"legend"; }
+p {
+  background:lime;
+  height:20px;
+}
+</style>
+</head>
+<body>
+<fieldset id="f1"><p></p></fieldset>
+<br>
+<fieldset id="f2"><p></p></fieldset>
+<br>
+<fieldset id="f3"></fieldset>
+<script>
+function doTest() {
+  f1.appendChild(document.createElement('legend'));
+  f2.insertBefore(document.createElement('legend'), f2.firstChild);
+  f3.appendChild(document.createElement('legend'));
+  document.documentElement.removeAttribute("class");
+}
+window.addEventListener("MozReftestInvalidate", doTest);
+</script>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-hidden-1-ref.html

@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="width:200px; height:200px; padding:0">
+  <legend>Legend</legend>
+  <div style="overflow:hidden; height:100%;">
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+  </div>
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-hidden-1.html

@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="overflow:hidden; width:200px; height:200px; padding:0">
+  <legend>Legend</legend>
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-intrinsic-width-1-ref.html

@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="width:0; padding:0;">
+  <div style="width:400px; height:200px;"></div>
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-intrinsic-width-1.html

@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="padding:50px; float:left;">
+  <div style="width:300px; height:100px;"></div>
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-overflow-auto-1-ref.html

@@ -0,0 +1,52 @@
+<!DOCTYPE HTML>
+<html><head>
+    <meta charset="utf-8">
+    <title>Testcase for bug 261037</title>
+    <style type="text/css">
+fieldset, div { 
+  background:pink;
+  overflow:auto;
+  height:100px;
+  margin:0; padding:0; border:0;
+}
+p {
+  background:blue;
+  height:100px;
+  margin:0; padding:0;
+}
+.overflow {
+  height:110px;
+}
+.abs {
+  position:absolute;
+  width:100px;
+  top:250px;
+}
+p.abs {
+  top:0;left:0;
+}
+.b { border:10px solid black; }
+.p { padding: 7px 0; }
+.p p { height:114px; }
+    </style>
+</head>
+<body>
+
+<div><p></p></div>
+<br>
+<div><p class="overflow"></p></div>
+<br>
+<div class="abs"><p class="abs"></p></div>
+<br>
+<div class="abs" style="left:120px"><p class="abs overflow"></p></div>
+<br>
+<div class="abs b" style="left:240px"><p class="abs"></p></div>
+<br>
+<div class="abs b" style="left:370px"><p class="abs overflow"></p></div>
+<br>
+<div class="abs b p" style="left:510px"><p class="abs"></p></div>
+<br>
+<div class="abs b p" style="left:640px"><p class="abs overflow"></p></div>
+
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-overflow-auto-1.html

@@ -0,0 +1,52 @@
+<!DOCTYPE HTML>
+<html><head>
+    <meta charset="utf-8">
+    <title>Testcase for bug 261037</title>
+    <style type="text/css">
+fieldset, div { 
+  background:pink;
+  overflow:auto;
+  height:100px;
+  margin:0; padding:0; border:0;
+}
+p {
+  background:blue;
+  height:100px;
+  margin:0; padding:0;
+}
+.overflow {
+  height:110px;
+}
+.abs {
+  position:absolute;
+  width:100px;
+  top:250px;
+}
+p.abs {
+  top:0;left:0;
+}
+.b { border:10px solid black; }
+.p { padding: 7px 0; }
+.p p { height:114px; }
+    </style>
+</head>
+<body>
+
+<fieldset><p></p></fieldset>
+<br>
+<fieldset><p class="overflow"></p></fieldset>
+<br>
+<fieldset class="abs"><p class="abs"></p></fieldset>
+<br>
+<fieldset class="abs" style="left:120px"><p class="abs overflow"></p></fieldset>
+<br>
+<fieldset class="abs b" style="left:240px"><p class="abs"></p></fieldset>
+<br>
+<fieldset class="abs b" style="left:370px"><p class="abs overflow"></p></fieldset>
+<br>
+<fieldset class="abs b p" style="left:510px"><p class="abs"></p></fieldset>
+<br>
+<fieldset class="abs b p" style="left:640px"><p class="abs overflow"></p></fieldset>
+
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-percentage-padding-1-ref.html

@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="width:700px; border:2px solid green; overflow:hidden">
+  <fieldset style="padding:140px; width:400px;">
+    <legend>Legend</legend>
+    TextTextTextTextTextText
+  </fieldset>
+  <fieldset style="padding:140px; display:inline;">
+    <legend>Legend</legend>
+    TextTextTextTextTextText
+  </fieldset>
+  <fieldset style="padding:140px; float:left;">
+    <legend>Legend</legend>
+    TextTextTextTextTextText
+  </fieldset>
+</div>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-percentage-padding-1.html

@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="width:700px; border:2px solid green; overflow:hidden">
+  <fieldset style="padding:20%; width:400px;">
+    <legend>Legend</legend>
+    TextTextTextTextTextText
+  </fieldset>
+  <fieldset style="padding:20%; display:inline;">
+    <legend>Legend</legend>
+    TextTextTextTextTextText
+  </fieldset>
+  <fieldset style="padding:20%; float:left;">
+    <legend>Legend</legend>
+    TextTextTextTextTextText
+  </fieldset>
+</div>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-scroll-1-ref.html

@@ -0,0 +1,9 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="width:200px; height:200px; padding:0">
+  <legend>Legend</legend>
+  <div style="overflow:scroll; height:100%">
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-scroll-1.html

@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="overflow:scroll; width:200px; height:200px; padding:0">
+  <legend>Legend</legend>
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-scrolled-1-ref.html

@@ -0,0 +1,24 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="width:200px; height:200px; padding:0">
+  <legend style="overflow:hidden">Legend</legend>
+  <div id="d" style="overflow:hidden; height:100%;">
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+    <p>Hello Kitty
+  </div>
+</fieldset>
+<script>
+d.scrollTop = 20;
+</script>
+</body>
+</html>

layout/reftests/forms/fieldset/fieldset-scrolled-1.html

@@ -0,0 +1,27 @@
+<!DOCTYPE HTML>
+<html class="reftest-wait">
+<body>
+<fieldset id="f" style="overflow:hidden; width:200px; height:200px; padding:0">
+  <legend style="overflow:hidden">Legend</legend>
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+  <p>Hello Kitty
+</fieldset>
+<script>
+f.scrollTop = 0;
+function doTest() {
+  f.scrollTop = 20;
+  document.documentElement.removeAttribute("class");
+}
+window.addEventListener("MozReftestInvalidate", doTest);
+</script>
+</body>
+</html>

layout/reftests/forms/fieldset/positioned-container-1-ref.html

@@ -0,0 +1,11 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset style="position:relative; overflow:hidden; width:500px; height:500px;">
+  <legend>Legend</legend>
+  <div style="height:1000px;">
+    <div style="position:absolute; left:20px; top:20px; background:yellow;">Abs-pos</div>
+  </div>
+</fieldset>
+</body>
+</html>

layout/reftests/forms/fieldset/positioned-container-1.html

@@ -0,0 +1,14 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<fieldset id="f" style="position:relative; overflow:hidden; width:500px; height:500px;">
+  <legend>Legend</legend>
+  <div style="height:1000px;">
+    <div style="position:absolute; left:20px; top:50px; background:yellow;">Abs-pos</div>
+  </div>
+</fieldset>
+<script>
+f.scrollTop = 30;
+</script>
+</body>
+</html>

layout/reftests/forms/fieldset/reftest.list

@@ -0,0 +1,8 @@
+== dynamic-legend-scroll-1.html dynamic-legend-scroll-1-ref.html
+== fieldset-hidden-1.html fieldset-hidden-1-ref.html
+== fieldset-intrinsic-width-1.html fieldset-intrinsic-width-1-ref.html
+== fieldset-percentage-padding-1.html fieldset-percentage-padding-1-ref.html
+== fieldset-scroll-1.html fieldset-scroll-1-ref.html
+== fieldset-scrolled-1.html fieldset-scrolled-1-ref.html
+== fieldset-overflow-auto-1.html fieldset-overflow-auto-1-ref.html
+== positioned-container-1.html positioned-container-1-ref.html

layout/reftests/forms/reftest.list

@@ -6,6 +6,9 @@ include button/reftest.list
 # legend element
 include legend/reftest.list
 
+# fieldset element
+include fieldset/reftest.list
+
 # placeholder
 include placeholder/reftest.list
 

layout/style/forms.css

@@ -14,6 +14,8 @@
   display: block;
   unicode-bidi: inherit;
   text-overflow: inherit;
+  overflow: inherit;
+  padding: inherit;
   height: 100%;   /* Need this so percentage heights of kids work right */
 }