Remove WrapperWorldType from V8 binding

Source/bindings/v8/DOMWrapperWorld.h

Index: Source/bindings/v8/DOMWrapperWorld.h
diff --git a/Source/bindings/v8/DOMWrapperWorld.h b/Source/bindings/v8/DOMWrapperWorld.h
index 69385c1184dc2c3edb715e71a2c20d0b2fab9f92..b9e0533c995e14ce35a617bd5743a9e6090dff5e 100644
--- a/Source/bindings/v8/DOMWrapperWorld.h
+++ b/Source/bindings/v8/DOMWrapperWorld.h
@@ -71,26 +71,21 @@ public:
 
     static DOMWrapperWorld* world(v8::Handle<v8::Context> context)
     {
+        ASSERT(!context.IsEmpty());
         return V8PerContextData::world(context);
     }
 
     // Will return null if there is no DOMWrapperWorld for the current context.
     static DOMWrapperWorld* current(v8::Isolate* isolate)
     {
-        v8::Handle<v8::Context> context = isolate->GetCurrentContext();
-        if (context.IsEmpty()) {
-            // If a worker thread calls current() with an empty context, it means that there is no DOMWrapperWorld.
-            if (!isMainThread())
-                return 0;
-
-            // If the main thread calls current() with an empty context, it's possible that
-            // current() is being called while window is being initialized.
+        if (isMainThread() && worldOfInitializingWindow) {
+            // It's possible that current() is being called while window is being initialized.
             // In order to make current() workable during the initialization phase,
             // we cache the world of the initializing window on worldOfInitializingWindow.
             // If there is no initiazing window, worldOfInitializingWindow is 0.
             return worldOfInitializingWindow;
         }
-        return world(context);
+        return world(isolate->GetCurrentContext());
     }
 
     static DOMWrapperWorld* mainWorld();