Get rid of anonymous table* wrappers when they are no longer needed.

Source/core/rendering/RenderObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2789 matching lines @@
     RenderObject* destroyRoot = this;
     for (RenderObject* destroyRootParent = destroyRoot->parent(); destroyRootParent && destroyRootParent->isAnonymous(); destroyRoot = destroyRootParent, destroyRootParent = destroyRootParent->parent()) {
         // Anonymous block continuations are tracked and destroyed elsewhere (see the bottom of RenderBlock::removeChild)
         if (destroyRootParent->isRenderBlock() && toRenderBlock(destroyRootParent)->isAnonymousBlockContinuation())
             break;
         // Render flow threads are tracked by the FlowThreadController, so we can't destroy them here.
         // Column spans are tracked elsewhere.
         if (destroyRootParent->isRenderFlowThread() || destroyRootParent->isAnonymousColumnSpanBlock())
             break;
 
-        if (destroyRootParent->slowFirstChild() != this || destroyRootParent->slowLastChild() != this)
+        if (destroyRootParent->slowFirstChild() != destroyRoot || destroyRootParent->slowLastChild() != destroyRoot)
+            break; // Need to keep the anonymous parent, since it won't become empty by the removal of this renderer.
+
+        // If it's an anonymous table* renderer ancestor that's going to become empty, destroy it,
+        // no matter how far up in the ancestry it is. Otherwise, stop when we have walked one level
+        // up. Table* renderers is the only case where we know that it's necessary and safe to walk
+        // further up than one level.
+        if (destroyRoot != this && !destroyRootParent->isTableCell() && !destroyRootParent->isTableRow() && !destroyRootParent->isTableSection() && !destroyRootParent->isTable())

[Julien - ping for review, 2014/09/08 21:28:49]

This seems very artificial to limit this to table and table parts. I agree with
you that they are the only example where we will walk more than a single level
but this may change and thus I don't think we should special-case table.

[mstensho (USE GERRIT), 2014/09/16 13:00:07]

Done.

             break;
     }
 
     destroyRoot->destroy();
 
     // WARNING: |this| is deleted here.
 }
 
 void RenderObject::destroy()
 {
@@ skipping 661 matching lines @@
 {
     if (object1) {
         const blink::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif