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

Source/bindings/v8/custom/V8InjectedScriptHostCustom.cpp

 /*
  * Copyright (C) 2007-2011 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 255 matching lines @@
     if (args.Length() < 1)
         return;
 
     v8::Local<v8::Value> value = args[0];
     if (!V8Node::HasInstance(value, args.GetIsolate(), worldType(args.GetIsolate())))
         return;
     Node* node = V8Node::toNative(value->ToObject());
     if (!node)
         return;
     // This can only happen for orphan DocumentType nodes.
-    Document* document = node->document();
-    if (!node->document())
-        return;
+    Document& document = node->document();
 
     InjectedScriptHost* host = V8InjectedScriptHost::toNative(args.Holder());
     Vector<EventListenerInfo> listenersArray;
     host->getEventListenersImpl(node, listenersArray);
 
     v8::Local<v8::Object> result = v8::Object::New();
     for (size_t i = 0; i < listenersArray.size(); ++i) {
-        v8::Handle<v8::Array> listeners = getJSListenerFunctions(document, listenersArray[i]);
+        v8::Handle<v8::Array> listeners = getJSListenerFunctions(&document, listenersArray[i]);
         if (!listeners->Length())
             continue;
         AtomicString eventType = listenersArray[i].eventType;
         result->Set(v8String(eventType, args.GetIsolate()), listeners);
     }
 
     v8SetReturnValue(args, result);
 }
 
 void V8InjectedScriptHost::inspectMethodCustom(const v8::FunctionCallbackInfo<v8::Value>& args)
@@ skipping 134 matching lines @@
     int lineNumber;
     int columnNumber;
     if (!getFunctionLocation(args, &scriptId, &lineNumber, &columnNumber))
         return;
 
     InjectedScriptHost* host = V8InjectedScriptHost::toNative(args.Holder());
     host->unmonitorFunction(scriptId, lineNumber, columnNumber);
 }
 
 } // namespace WebCore