Bug 984711 part 4: Add back handling for nsStylePosition::mMinHeight having "eStyleUnit_Auto" in style system & general layout code. (no review; just an unbitrotted backout)

This reverts changeset 5db313632268 from bug 848539.

layout/base/nsLayoutUtils.cpp

@@ -3591,7 +3591,8 @@ GetPercentHeight(const nsStyleCoord& aStyle,
     if (minh > h)
       h = minh;
   } else {
-    NS_ASSERTION(pos->mMinHeight.HasPercent(),
+    NS_ASSERTION(pos->mMinHeight.HasPercent() ||
+                 pos->mMinHeight.GetUnit() == eStyleUnit_Auto,
                  "unknown min-height unit");
   }
 
@@ -3752,12 +3753,18 @@ nsLayoutUtils::IntrinsicForContainer(nsRenderingContext *aRenderingContext,
 
     // Handle elements with an intrinsic ratio (or size) and a specified
     // height, min-height, or max-height.
+    // NOTE: We treat "min-height:auto" as "0" for the purpose of this code,
+    // since that's what it means in all cases except for on flex items -- and
+    // even there, we're supposed to ignore it (i.e. treat it as 0) until the
+    // flex container explicitly considers it.
     const nsStyleCoord &styleHeight = stylePos->mHeight;
     const nsStyleCoord &styleMinHeight = stylePos->mMinHeight;
     const nsStyleCoord &styleMaxHeight = stylePos->mMaxHeight;
+
     if (styleHeight.GetUnit() != eStyleUnit_Auto ||
-        !(styleMinHeight.GetUnit() == eStyleUnit_Coord &&
+        !(styleMinHeight.GetUnit() == eStyleUnit_Auto || 
-          styleMinHeight.GetCoordValue() == 0) ||
+          (styleMinHeight.GetUnit() == eStyleUnit_Coord &&
+           styleMinHeight.GetCoordValue() == 0)) ||
         styleMaxHeight.GetUnit() != eStyleUnit_None) {
 
       nsSize ratio = aFrame->GetIntrinsicRatio();

layout/generic/nsHTMLReflowState.cpp

@@ -2627,8 +2627,13 @@ nsHTMLReflowState::ComputeMinMaxValues(nscoord aContainingBlockWidth,
   // Likewise, if we're a child of a flex container who's measuring our
   // intrinsic height, then we want to disregard our min-height.
 
+  // NOTE: We treat "min-height:auto" as "0" for the purpose of this code,
+  // since that's what it means in all cases except for on flex items -- and
+  // even there, we're supposed to ignore it (i.e. treat it as 0) until the
+  // flex container explicitly considers it.
   const nsStyleCoord &minHeight = mStylePosition->mMinHeight;
-  if ((NS_AUTOHEIGHT == aContainingBlockHeight &&
+  if (eStyleUnit_Auto == minHeight.GetUnit() ||
+      (NS_AUTOHEIGHT == aContainingBlockHeight &&
        minHeight.HasPercent()) ||
       (mFrameType == NS_CSS_FRAME_TYPE_INTERNAL_TABLE &&
        minHeight.IsCalcUnit() && minHeight.CalcHasPercent()) ||

layout/style/nsComputedDOMStyle.cpp

@@ -4103,7 +4103,17 @@ CSSValue*
 nsComputedDOMStyle::DoGetMinHeight()
 {
   nsROCSSPrimitiveValue *val = new nsROCSSPrimitiveValue;
-  SetValueToCoord(val, StylePosition()->mMinHeight, true,
+  nsStyleCoord minHeight = StylePosition()->mMinHeight;
+
+  if (eStyleUnit_Auto == minHeight.GetUnit()) {
+    // In non-flexbox contexts, "min-height: auto" means "min-height: 0"
+    // XXXdholbert For flex items, we should set |minHeight| to the
+    // -moz-min-content keyword, instead of 0, once we support -moz-min-content
+    // as a height value.
+    minHeight.SetCoordValue(0);
+  }
+
+  SetValueToCoord(val, minHeight, true,
                   &nsComputedDOMStyle::GetCBContentHeight);
   return val;
 }

layout/style/nsRuleNode.cpp

@@ -7453,11 +7453,6 @@ nsRuleNode::ComputePositionData(void* aStartStruct,
              SETCOORD_UNSET_INITIAL,
            aContext, mPresContext, canStoreInRuleTree);
 
-  // Make 'auto' values for min-height compute to 0
-  if (pos->mMinHeight.GetUnit() == eStyleUnit_Auto) {
-    pos->mMinHeight.SetCoordValue(0);
-  }
-
   // box-sizing: enum, inherit, initial
   SetDiscrete(*aRuleData->ValueForBoxSizing(),
               pos->mBoxSizing, canStoreInRuleTree,

layout/style/nsStyleStruct.cpp

@@ -1234,7 +1234,7 @@ nsStylePosition::nsStylePosition(void)
   mMinWidth.SetAutoValue();
   mMaxWidth.SetNoneValue();
   mHeight.SetAutoValue();
-  mMinHeight.SetCoordValue(0);
+  mMinHeight.SetAutoValue();
   mMaxHeight.SetNoneValue();
   mFlexBasis.SetAutoValue();
 

layout/style/nsStyleStruct.h

@@ -1381,7 +1381,13 @@ struct nsStylePosition {
   // FIXME: We should probably change the assumption to be the other way
   // around.
   bool HeightDependsOnContainer() const
-    { return HeightCoordDependsOnContainer(mHeight); }
+    {
+      return mHeight.GetUnit() == eStyleUnit_Auto || // CSS 2.1, 10.6.4, item (5)
+        HeightCoordDependsOnContainer(mHeight);
+    }
+
+  // NOTE: The comment above MinWidthDependsOnContainer about flex items
+  // applies here, too.
   bool MinHeightDependsOnContainer() const
     { return HeightCoordDependsOnContainer(mMinHeight); }
   bool MaxHeightDependsOnContainer() const
@@ -1395,10 +1401,7 @@ struct nsStylePosition {
 private:
   static bool WidthCoordDependsOnContainer(const nsStyleCoord &aCoord);
   static bool HeightCoordDependsOnContainer(const nsStyleCoord &aCoord)
-  {
+    { return aCoord.HasPercent(); }
-    return aCoord.GetUnit() == eStyleUnit_Auto || // CSS 2.1, 10.6.4, item (5)
-           aCoord.HasPercent();
-  }
 };
 
 struct nsStyleTextOverflowSide {