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

Source/core/rendering/RenderRegion.cpp

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 191 matching lines @@
 }
 
 void RenderRegion::checkRegionStyle()
 {
     ASSERT(m_flowThread);
     bool customRegionStyle = false;
 
     // FIXME: Region styling doesn't work for pseudo elements.
     if (node()) {
         Element* regionElement = toElement(node());
-        customRegionStyle = view()->document()->styleResolver()->checkRegionStyle(regionElement);
+        customRegionStyle = view()->document().styleResolver()->checkRegionStyle(regionElement);
     }
     setHasCustomRegionStyle(customRegionStyle);
     m_flowThread->checkRegionsWithStyling();
 }
 
 void RenderRegion::incrementAutoLogicalHeightCount()
 {
     ASSERT(isValid());
     ASSERT(m_hasAutoLogicalHeight);
 
@@ skipping 308 matching lines @@
 {
     RenderBlock::willBeRemovedFromTree();
 
     detachRegion();
 }
 
 PassRefPtr<RenderStyle> RenderRegion::computeStyleInRegion(const RenderObject* object)
 {
     ASSERT(object);
     ASSERT(object->view());
-    ASSERT(object->view()->document());
     ASSERT(!object->isAnonymous());
     ASSERT(object->node() && object->node()->isElementNode());
 
     // FIXME: Region styling fails for pseudo-elements because the renderers don't have a node.
     Element* element = toElement(object->node());
-    RefPtr<RenderStyle> renderObjectRegionStyle = object->view()->document()->styleResolver()->styleForElement(element, 0, DisallowStyleSharing, MatchAllRules, this);
+    RefPtr<RenderStyle> renderObjectRegionStyle = object->view()->document().styleResolver()->styleForElement(element, 0, DisallowStyleSharing, MatchAllRules, this);
 
     return renderObjectRegionStyle.release();
 }
 
 void RenderRegion::computeChildrenStyleInRegion(const RenderObject* object)
 {
     for (RenderObject* child = object->firstChild(); child; child = child->nextSibling()) {
 
         RenderObjectRegionStyleMap::iterator it = m_renderObjectRegionStyle.find(child);
 
@@ skipping 88 matching lines @@
 
     LayoutUnit autoHeight = hasOverrideHeight() ? overrideLogicalContentHeight() : computedAutoHeight();
 
     LayoutUnit newLogicalHeight = autoHeight + borderAndPaddingLogicalHeight();
     ASSERT(newLogicalHeight < LayoutUnit::max() / 2);
     if (newLogicalHeight > logicalHeight())
         setLogicalHeight(newLogicalHeight);
 }
 
 } // namespace WebCore