Have Node::document() return a reference instead of a pointer

Source/core/rendering/RenderRuby.cpp

 /*
  * Copyright (C) 2009 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 67 matching lines @@
 
 static inline RenderBlock* rubyAfterBlock(const RenderObject* ruby)
 {
     RenderObject* child = ruby->lastChild();
     return isRubyAfterBlock(child) ? toRenderBlock(child) : 0;
 }
 
 static RenderBlock* createAnonymousRubyInlineBlock(RenderObject* ruby)
 {
     RefPtr<RenderStyle> newStyle = RenderStyle::createAnonymousStyleWithDisplay(ruby->style(), INLINE_BLOCK);
-    RenderBlock* newBlock = RenderBlock::createAnonymous(ruby->document());
+    RenderBlock* newBlock = RenderBlock::createAnonymous(&ruby->document());
     newBlock->setStyle(newStyle.release());
     return newBlock;
 }
 
 static RenderRubyRun* lastRubyRun(const RenderObject* ruby)
 {
     RenderObject* child = ruby->lastChild();
     if (child && !child->isRubyRun())
         child = child->previousSibling();
     ASSERT(!child || child->isRubyRun() || child->isBeforeContent() || child == rubyBeforeBlock(ruby));
@@ skipping 213 matching lines @@
         return;
     }
 
     // Otherwise find the containing run and remove it from there.
     RenderRubyRun* run = findRubyRunParent(child);
     ASSERT(run);
     run->removeChild(child);
 }
 
 } // namespace WebCore