Don't leave stale pointers into m_grid

Source/core/rendering/RenderBlock.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 31 matching lines @@
 #include "core/rendering/HitTestLocation.h"
 #include "core/rendering/HitTestResult.h"
 #include "core/rendering/InlineIterator.h"
 #include "core/rendering/InlineTextBox.h"
 #include "core/rendering/LayoutRepainter.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderCombineText.h"
 #include "core/rendering/RenderDeprecatedFlexibleBox.h"
 #include "core/rendering/RenderFlexibleBox.h"
 #include "core/rendering/RenderFlowThread.h"
+#include "core/rendering/RenderGrid.h"
 #include "core/rendering/RenderInline.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderMarquee.h"
 #include "core/rendering/RenderRegion.h"
 #include "core/rendering/RenderTableCell.h"
 #include "core/rendering/RenderTextControl.h"
 #include "core/rendering/RenderTextFragment.h"
 #include "core/rendering/RenderTheme.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/shapes/ShapeOutsideInfo.h"
@@ skipping 983 matching lines @@
         if (child->nextSibling())
             child->nextSibling()->setPreviousSibling(child->previousSibling());
     }
 
     child->children()->setFirstChild(0);
     child->m_next = 0;
 
     // Remove all the information in the flow thread associated with the leftover anonymous block.
     child->removeFromRenderFlowThread();
 
+    // RenderGrid keeps track of its children, we must notify it about changes in the tree.
+    if (child->parent()->isRenderGrid())
+        toRenderGrid(child->parent())->dirtyGrid();
+
     child->setParent(0);
     child->setPreviousSibling(0);
     child->setNextSibling(0);
 
     child->destroy();
 }
 
 static bool canMergeContiguousAnonymousBlocks(RenderObject* oldChild, RenderObject* prev, RenderObject* next)
 {
     if (oldChild->documentBeingDestroyed() || oldChild->isInline() || oldChild->virtualContinuation())
@@ skipping 3945 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace WebCore