Make DOMWrapperWorlds easier to use

Source/bindings/v8/V8MutationCallback.cpp

Index: Source/bindings/v8/V8MutationCallback.cpp
diff --git a/Source/bindings/v8/V8MutationCallback.cpp b/Source/bindings/v8/V8MutationCallback.cpp
index 75c1937910c0e0eec8f15dfad4e8d6a9816a775c..6618cc37cb342fb15cf26cb974f927e52c3afd09 100644
--- a/Source/bindings/v8/V8MutationCallback.cpp
+++ b/Source/bindings/v8/V8MutationCallback.cpp
@@ -44,7 +44,7 @@ void WeakHandleListener<V8MutationCallback>::callback(v8::Isolate*, v8::Persiste
 V8MutationCallback::V8MutationCallback(v8::Handle<v8::Function> callback, ScriptExecutionContext* context, v8::Handle<v8::Object> owner, v8::Isolate* isolate)
     : ActiveDOMCallback(context)
     , m_callback(callback)
-    , m_world(DOMWrapperWorld::isolatedWorld(v8::Context::GetCurrent()))
+    , m_world(DOMWrapperWorld::current(context))
 {
     owner->SetHiddenValue(V8HiddenPropertyName::callback(), callback);
     WeakHandleListener<V8MutationCallback>::makeWeak(isolate, m_callback.get(), this);