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

Source/bindings/v8/ScriptEventListener.cpp

Index: Source/bindings/v8/ScriptEventListener.cpp
diff --git a/Source/bindings/v8/ScriptEventListener.cpp b/Source/bindings/v8/ScriptEventListener.cpp
index 1d4a7f3a5ff1d3027f7cfd7a217634d7c6fc87c2..f614b11a249a26aa673c7f777d8ff4645beb4ce9 100644
--- a/Source/bindings/v8/ScriptEventListener.cpp
+++ b/Source/bindings/v8/ScriptEventListener.cpp
@@ -60,12 +60,12 @@ PassRefPtr<V8LazyEventListener> createAttributeEventListener(Node* node, const Q
     TextPosition position(OrdinalNumber::fromZeroBasedInt(1), OrdinalNumber::first());
     String sourceURL;
 
-    if (Frame* frame = node->document()->frame()) {
+    if (Frame* frame = node->document().frame()) {
         ScriptController* scriptController = frame->script();
         if (!scriptController->canExecuteScripts(AboutToExecuteScript))
             return 0;
         position = scriptController->eventHandlerPosition();
-        sourceURL = node->document()->url().string();
+        sourceURL = node->document().url().string();
     }
 
     return V8LazyEventListener::create(name.localName().string(), eventParameterName(node->isSVGElement()), value, sourceURL, position, node);