Add toWebCoreString() / toWebCoreAtomicString() overloads taking a v8::String

Source/bindings/v8/custom/V8WorkerGlobalScopeCustom.cpp

Index: Source/bindings/v8/custom/V8WorkerGlobalScopeCustom.cpp
diff --git a/Source/bindings/v8/custom/V8WorkerGlobalScopeCustom.cpp b/Source/bindings/v8/custom/V8WorkerGlobalScopeCustom.cpp
index 79b0749055ca9ed7f40b70d4a4d150b7f66cce45..2c3dc2f9ed2957060e20f046fe24bf13744add67 100644
--- a/Source/bindings/v8/custom/V8WorkerGlobalScopeCustom.cpp
+++ b/Source/bindings/v8/custom/V8WorkerGlobalScopeCustom.cpp
@@ -70,7 +70,7 @@ void SetTimeoutOrInterval(const v8::FunctionCallbackInfo<v8::Value>& args, bool
                 return;
             }
         }
-        action = adoptPtr(new ScheduledAction(v8Context, toWebCoreString(function), workerGlobalScope->url(), args.GetIsolate()));
+        action = adoptPtr(new ScheduledAction(v8Context, toWebCoreString(function.As<v8::String>()), workerGlobalScope->url(), args.GetIsolate()));
     } else if (function->IsFunction()) {
         size_t paramCount = argumentCount >= 2 ? argumentCount - 2 : 0;
         OwnArrayPtr<v8::Local<v8::Value> > params;