Mark when we may have been invalidated to early out on repaintTreeAfterLayout.

Source/core/rendering/RenderBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 888 matching lines @@
         next = child->nextSiblingBox();
 
         // FIXME: this should only be set from clearNeedsLayout crbug.com/361250
         child->setLayoutDidGetCalled(true);
 
         if (childToExclude == child)
             continue; // Skip this child, since it will be positioned by the specialized subclass (fieldsets and ruby runs).
 
         updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, child);
 
+        child->setMayNeedInvalidation(true);
+
         if (child->isOutOfFlowPositioned()) {
             child->containingBlock()->insertPositionedObject(child);
             adjustPositionedBlock(child, marginInfo);
             continue;
         }
         if (child->isFloating()) {
             insertFloatingObject(child);
             adjustFloatingBlock(marginInfo);
             continue;
         }
@@ skipping 1389 matching lines @@
     FloatingObjectSetIterator end = floatingObjectSet.end();
     // Now walk through the set of unpositioned floats and place them.
     for (; it != end; ++it) {
         FloatingObject* floatingObject = *it;
         // The containing block is responsible for positioning floats, so if we have floats in our
         // list that come from somewhere else, do not attempt to position them.
         if (floatingObject->renderer()->containingBlock() != this)
             continue;
 
         RenderBox* childBox = floatingObject->renderer();
+        childBox->setMayNeedInvalidation(true);
 
         LayoutUnit childLogicalLeftMargin = style()->isLeftToRightDirection() ? marginStartForChild(childBox) : marginEndForChild(childBox);
         LayoutRect oldRect = childBox->frameRect();
 
         if (childBox->style()->clear() & CLEFT)
             logicalTop = max(lowestFloatLogicalBottom(FloatingObject::FloatLeft), logicalTop);
         if (childBox->style()->clear() & CRIGHT)
             logicalTop = max(lowestFloatLogicalBottom(FloatingObject::FloatRight), logicalTop);
 
         LayoutPoint floatLogicalLocation = computeLogicalLocationForFloat(floatingObject, logicalTop);
@@ skipping 465 matching lines @@
 RenderBlockFlow::RenderBlockFlowRareData& RenderBlockFlow::ensureRareData()
 {
     if (m_rareData)
         return *m_rareData;
 
     m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
     return *m_rareData;
 }
 
 } // namespace WebCore