Fix a regression when position:static with absolute child changed to relative

Source/core/layout/LayoutBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 269 matching lines @@
         bool newHasTransformRelatedProperty = newStyle.hasTransformRelatedProperty();
         bool oldStyleIsContainer = oldStyle->position() != StaticPosition || oldHasTransformRelatedProperty;
 
         if (oldStyleIsContainer && (newStyle.position() == StaticPosition || (oldHasTransformRelatedProperty && !newHasTransformRelatedProperty))) {
             // Clear our positioned objects list. Our absolutely positioned descendants will be
             // inserted into our containing block's positioned objects list during layout.
             removePositionedObjects(0, NewContainingBlock);
         } else if (!oldStyleIsContainer && (newStyle.position() != StaticPosition || newHasTransformRelatedProperty)) {
             // Remove our absolutely positioned descendants from their current containing block.
             // They will be inserted into our positioned objects list during layout.
-            if (LayoutBlock* cb = containingBlock())
+            if (LayoutBlock* cb = containerForAbsolutePosition())
                 cb->removePositionedObjects(this, NewContainingBlock);
         }
     }
 
     LayoutBox::styleWillChange(diff, newStyle);
 }
 
 static bool borderOrPaddingLogicalWidthChanged(const ComputedStyle& oldStyle, const ComputedStyle& newStyle)
 {
     if (newStyle.isHorizontalWritingMode()) {
@@ skipping 1204 matching lines @@
 {
     if (gPositionedDescendantsMap)
         return gPositionedDescendantsMap->get(this);
     return nullptr;
 }
 
 void LayoutBlock::insertPositionedObject(LayoutBox* o)
 {
     ASSERT(!isAnonymousBlock());
     insertIntoTrackedLayoutBoxMaps(o, gPositionedDescendantsMap, gPositionedContainerMap);
+    ASSERT(gPositionedContainerMap->get(o)->size() == 1);
 }
 
 void LayoutBlock::removePositionedObject(LayoutBox* o)
 {
     removeFromTrackedLayoutBoxMaps(o, gPositionedDescendantsMap, gPositionedContainerMap);
 }
 
 void LayoutBlock::removePositionedObjects(LayoutBlock* o, ContainingBlockState containingBlockState)
 {
     TrackedLayoutBoxListHashSet* positionedDescendants = positionedObjects();
@@ skipping 1410 matching lines @@
 void LayoutBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const LayoutObject* obj) const
 {
     showLayoutObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink