Bug 608987. Fixing compartment mismatch when setting up the proto chain of a plugin object. r=gal@uci.edu, a=blocker

dom/base/nsDOMClassInfo.cpp

@@ -9611,6 +9611,11 @@ nsHTMLPluginObjElementSH::SetupProtoChain(nsIXPConnectWrappedNative *wrapper,
     return NS_OK;
   }
 
+  JSAutoEnterCompartment ac;
+  if (!ac.enter(cx, obj)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
   nsCOMPtr<nsIPluginInstance> pi;
   nsresult rv = GetPluginInstanceIfSafe(wrapper, obj, getter_AddRefs(pi));
   NS_ENSURE_SUCCESS(rv, rv);