Revert of Limit the usage of SharedPersistent to ScriptValue only

Source/bindings/v8/V8NPObject.cpp

Index: Source/bindings/v8/V8NPObject.cpp
diff --git a/Source/bindings/v8/V8NPObject.cpp b/Source/bindings/v8/V8NPObject.cpp
index 53425a33adc1d57c6329b9b24e961a4ccb870898..f3717624314fbce974b1e1c6f1f06691d87f97de 100644
--- a/Source/bindings/v8/V8NPObject.cpp
+++ b/Source/bindings/v8/V8NPObject.cpp
@@ -81,11 +81,10 @@
             element = V8HTMLEmbedElement::toNative(info.Holder());
         else
             element = V8HTMLObjectElement::toNative(info.Holder());
-        ScriptValue wrapper = element->pluginWrapper();
-        if (!wrapper.hasNoValue()) {
+        if (RefPtr<SharedPersistent<v8::Object> > wrapper = element->pluginWrapper()) {
             v8::Isolate* isolate = v8::Isolate::GetCurrent();
             v8::HandleScope handleScope(isolate);
-            npObject = v8ObjectToNPObject(v8::Handle<v8::Object>::Cast(wrapper.v8Value()));
+            npObject = v8ObjectToNPObject(wrapper->newLocal(isolate));
         } else
             npObject = 0;
     } else {