Bug 1051663 - Correct |this| in REQUEST_DIAL_EMERGENCY_CALL. r=hsinyi

dom/system/gonk/ril_worker.js

@@ -5564,7 +5564,7 @@ RilObject.prototype[REQUEST_DIAL] = function REQUEST_DIAL(length, options) {
   }
 };
 RilObject.prototype[REQUEST_DIAL_EMERGENCY_CALL] = function REQUEST_DIAL_EMERGENCY_CALL(length, options) {
-  RilObject.prototype[REQUEST_DIAL](length, options);
+  RilObject.prototype[REQUEST_DIAL].call(this, length, options);
 };
 RilObject.prototype[REQUEST_GET_IMSI] = function REQUEST_GET_IMSI(length, options) {
   if (options.rilRequestError) {