Bug 729367 - Add write barrier flag to NPAPI class (r=igor)

dom/plugins/base/nsJSNPRuntime.cpp

@@ -209,7 +209,7 @@ NPObjectMember_Trace(JSTracer *trc, JSObject *obj);
 
 static JSClass sNPObjectMemberClass =
   {
-    "NPObject Ambiguous Member class", JSCLASS_HAS_PRIVATE,
+    "NPObject Ambiguous Member class", JSCLASS_HAS_PRIVATE | JSCLASS_IMPLEMENTS_BARRIERS,
     JS_PropertyStub, JS_PropertyStub,
     JS_PropertyStub, JS_StrictPropertyStub, JS_EnumerateStub,
     JS_ResolveStub, NPObjectMember_Convert,