Bug 869800 - Stop using calling JS_SetGlobalObject in workers. r=bent

This makes workers the first consumer to be weaned off this API. \o/

dom/workers/WorkerPrivate.cpp

@@ -704,8 +704,6 @@ public:
     }
 
     JSAutoCompartment ac(aCx, global);
-    JS_SetGlobalObject(aCx, global);
-
     return scriptloader::LoadWorkerScript(aCx);
   }
 };