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

Source/core/css/CSSStyleSheet.cpp

Index: Source/core/css/CSSStyleSheet.cpp
diff --git a/Source/core/css/CSSStyleSheet.cpp b/Source/core/css/CSSStyleSheet.cpp
index 6a3ed58134b4f6e388ef92079670f5b72016a4db..49ed4a18932c0744ea4ce5d7ee6037f97bfc33d1 100644
--- a/Source/core/css/CSSStyleSheet.cpp
+++ b/Source/core/css/CSSStyleSheet.cpp
@@ -80,7 +80,7 @@ PassRefPtr<CSSStyleSheet> CSSStyleSheet::create(PassRefPtr<StyleSheetContents> s
 
 PassRefPtr<CSSStyleSheet> CSSStyleSheet::createInline(Node* ownerNode, const KURL& baseURL, const TextPosition& startPosition, const String& encoding)
 {
-    CSSParserContext parserContext(ownerNode->document(), baseURL, encoding);
+    CSSParserContext parserContext(&ownerNode->document(), baseURL, encoding);
     RefPtr<StyleSheetContents> sheet = StyleSheetContents::create(baseURL.string(), parserContext);
     return adoptRef(new CSSStyleSheet(sheet.release(), ownerNode, true, startPosition));
 }
@@ -357,7 +357,7 @@ Document* CSSStyleSheet::ownerDocument() const
     const CSSStyleSheet* root = this;
     while (root->parentStyleSheet())
         root = root->parentStyleSheet();
-    return root->ownerNode() ? root->ownerNode()->document() : 0;
+    return root->ownerNode() ? &root->ownerNode()->document() : 0;
 }
 
 void CSSStyleSheet::clearChildRuleCSSOMWrappers()