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

Source/core/html/HTMLHtmlElement.cpp

Index: Source/core/html/HTMLHtmlElement.cpp
diff --git a/Source/core/html/HTMLHtmlElement.cpp b/Source/core/html/HTMLHtmlElement.cpp
index 704dde13454431374bf8a6309c5c3dcdbe4d1373..b28ac23a49564ed0228f346b89dadd72804502bc 100644
--- a/Source/core/html/HTMLHtmlElement.cpp
+++ b/Source/core/html/HTMLHtmlElement.cpp
@@ -61,13 +61,13 @@ bool HTMLHtmlElement::isURLAttribute(const Attribute& attribute) const
 void HTMLHtmlElement::insertedByParser()
 {
     // When parsing a fragment, its dummy document has a null parser.
-    if (!document()->parser() || !document()->parser()->documentWasLoadedAsPartOfNavigation())
+    if (!document().parser() || !document().parser()->documentWasLoadedAsPartOfNavigation())
         return;
 
-    if (!document()->frame())
+    if (!document().frame())
         return;
 
-    DocumentLoader* documentLoader = document()->frame()->loader()->documentLoader();
+    DocumentLoader* documentLoader = document().frame()->loader()->documentLoader();
     if (!documentLoader)
         return;
 
@@ -75,7 +75,7 @@ void HTMLHtmlElement::insertedByParser()
     if (manifest.isEmpty())
         documentLoader->applicationCacheHost()->selectCacheWithoutManifest();
     else
-        documentLoader->applicationCacheHost()->selectCacheWithManifest(document()->completeURL(manifest));
+        documentLoader->applicationCacheHost()->selectCacheWithManifest(document().completeURL(manifest));
 }
 
 }