Back out bug 588237, patches 2 through 5.

layout/base/nsCSSFrameConstructor.h

@@ -1464,9 +1464,9 @@ private:
    */
 public:
   nsIFrame* GetAbsoluteContainingBlock(nsIFrame* aFrame);
+private:
   nsIFrame* GetFloatContainingBlock(nsIFrame* aFrame);
 
-private:
   nsIContent* PropagateScrollToViewport();
 
   // Build a scroll frame: 

layout/generic/nsBlockFrame.cpp

@@ -4427,27 +4427,9 @@ nsBlockFrame::DrainSelfOverflowList()
   return true;
 }
 
-/**
- * Pushed floats are floats whose placeholders are in a previous
- * continuation.  They might themselves be next-continuations of a float
- * that partially fit in an earlier continuation, or they might be the
- * first continuation of a float that couldn't be placed at all.
- *
- * Pushed floats live permanently at the beginning of a block's float
- * list, where they must live *before* any floats whose placeholders are
- * in that block.
- *
- * Temporarily, during reflow, they also live on the pushed floats list,
- * which only holds them between (a) when one continuation pushes them to
- * its pushed floats list because they don't fit and (b) when the next
- * continuation pulls them onto the beginning of its float list.
- *
- * DrainPushedFloats sets up pushed floats the way we need them at the
- * start of reflow; they are then reflowed by ReflowPushedFloats (which
- * might push some of them on).  Floats with placeholders in this block
- * are reflowed by (nsBlockReflowState/nsLineLayout)::AddFloat, which
- * also maintains these invariants.
- */
+// This function assumes our prev-in-flow has completed reflow and its
+// mFloats may contain frames at the end of its float list, marked with
+// NS_FRAME_IS_PUSHED_FLOAT, that should be pulled to this block.
 void
 nsBlockFrame::DrainPushedFloats(nsBlockReflowState& aState)
 {
@@ -4460,58 +4442,16 @@ nsBlockFrame::DrainPushedFloats(nsBlockReflowState& aState)
   nsLayoutUtils::AssertNoDuplicateContinuations(this, mFloats);
 #endif
 
-  // If we're getting reflowed multiple times without our
-  // next-continuation being reflowed, we might need to pull back floats
-  // that we just put in the list to be pushed to our next-in-flow.
-  // But we can't pull any next-in-flows of floats on our own float list.
-  nsFrameList *ourPushedFloats = GetPushedFloats();
-  if (ourPushedFloats) {
-    // When we pull back floats, we want to put them with the pushed
-    // floats, which must live at the start of our float list, but we
-    // want them at the end of those pushed floats.
-    nsIFrame *insertionPrevSibling = nullptr; /* beginning of list */
-    for (nsIFrame* f = mFloats.FirstChild();
-         f && (f->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT);
-         f = f->GetNextSibling()) {
-      insertionPrevSibling = f;
-    }
-
-    nsPresContext *presContext = PresContext();
-    for (nsIFrame *f = ourPushedFloats->LastChild(), *next; f; f = next) {
-      next = f->GetPrevSibling();
-
-      if (!f->GetPrevContinuation()) {
-        nsPlaceholderFrame *placeholder =
-          presContext->FrameManager()->GetPlaceholderFrameFor(f);
-        nsIFrame *floatOriginalParent = presContext->PresShell()->
-          FrameConstructor()->GetFloatContainingBlock(placeholder);
-        if (floatOriginalParent != this) {
-          // This is a first continuation that was pushed from one of our
-          // previous continuations.  Take it out of the pushed floats
-          // list and put it in our floats list, before any of our
-          // floats, but after other pushed floats.
-          ourPushedFloats->RemoveFrame(f);
-          mFloats.InsertFrame(nullptr, insertionPrevSibling, f);
-        }
-      }
-    }
-
-    if (ourPushedFloats->IsEmpty()) {
-      delete RemovePushedFloats();
-    }
-  }
-
-  // After our prev-in-flow has completed reflow, it may have a pushed
-  // floats list, containing floats that we need to own.  Take these.
+  // Take any continuations we need to take from our prev-in-flow.
   nsBlockFrame* prevBlock = static_cast<nsBlockFrame*>(GetPrevInFlow());
-  if (prevBlock) {
-    nsFrameList *list = prevBlock->RemovePushedFloats();
-    if (list) {
-      if (list->NotEmpty()) {
-        mFloats.InsertFrames(this, nullptr, *list);
-      }
-      delete list;
+  if (!prevBlock)
+    return;
+  nsFrameList *list = prevBlock->RemovePushedFloats();
+  if (list) {
+    if (list->NotEmpty()) {
+      mFloats.InsertFrames(this, nullptr, *list);
     }
+    delete list;
   }
 }
 
@@ -5594,9 +5534,6 @@ nsBlockFrame::StealFrame(nsPresContext* aPresContext,
       nsFrameList* list = GetPushedFloats();
       if (list) {
         removed = list->RemoveFrameIfPresent(aChild);
-        if (list->IsEmpty()) {
-          delete RemovePushedFloats();
-        }
       }
     }
     return removed ? NS_OK : NS_ERROR_UNEXPECTED;
@@ -5913,8 +5850,6 @@ nsBlockFrame::ReflowPushedFloats(nsBlockReflowState& aState,
                                  nsReflowStatus&     aStatus)
 {
   nsresult rv = NS_OK;
-  // Pushed floats live at the start of our float list; see comment
-  // above nsBlockFrame::DrainPushedFloats.
   for (nsIFrame* f = mFloats.FirstChild(), *next;
        f && (f->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT);
        f = next) {
@@ -5961,9 +5896,17 @@ nsBlockFrame::ReflowPushedFloats(nsBlockReflowState& aState,
       continue;
     }
 
-    // Always call FlowAndPlaceFloat; we might need to place this float
-    // if didn't belong to this block the last time it was reflowed.
-    aState.FlowAndPlaceFloat(f);
+    if (NS_SUBTREE_DIRTY(f) || aState.mReflowState.ShouldReflowAllKids()) {
+      // Reflow
+      aState.FlowAndPlaceFloat(f);
+    }
+    else {
+      // Just reload the float region into the space manager
+      nsRect region = nsFloatManager::GetRegionFor(f);
+      aState.mFloatManager->AddFloat(f, region);
+      if (f->GetNextInFlow())
+        NS_MergeReflowStatusInto(&aStatus, NS_FRAME_OVERFLOW_INCOMPLETE);
+    }
 
     ConsiderChildOverflow(aOverflowAreas, f);
   }

layout/generic/nsBlockFrame.h

@@ -783,9 +783,7 @@ protected:
     return 0 != (GetStateBits() & NS_BLOCK_HAS_PUSHED_FLOATS);
   }
 
-  // Get the pushed floats list, which is used for *temporary* storage
-  // of floats during reflow, between when we decide they don't fit in
-  // this block until our next continuation takes them.
+  // Get the pushed floats list
   nsFrameList* GetPushedFloats() const;
   // Get the pushed floats list, or if there is not currently one,
   // make a new empty one.

layout/generic/nsBlockReflowState.cpp

@@ -465,9 +465,6 @@ nsBlockReflowState::AddFloat(nsLineLayout*       aLineLayout,
     // push it again, though.)  Likewise, if that previous reflow
     // reflowed this block but not its next continuation, we might need
     // to steal it from our own float-continuations list.
-    //
-    // For more about pushed floats, see the comment above
-    // nsBlockFrame::DrainPushedFloats.
     nsBlockFrame *floatParent =
       static_cast<nsBlockFrame*>(aFloat->GetParent());
     floatParent->StealFrame(mPresContext, aFloat);