Bug 1181871 P2 Fix ServiceWorkerManager usage of stack-based ErrorResult. r=ehsan

dom/workers/ServiceWorkerManager.cpp

@@ -1639,6 +1639,7 @@ DispatchExtendableEventOnWorkerScope(JSContext* aCx,
   ErrorResult result;
   result = aWorkerScope->DispatchDOMEvent(nullptr, aEvent, nullptr, nullptr);
   if (result.Failed() || internalEvent->mFlags.mExceptionHasBeenRisen) {
+    result.SuppressException();
     return nullptr;
   }
 
@@ -1648,6 +1649,7 @@ DispatchExtendableEventOnWorkerScope(JSContext* aCx,
     waitUntilPromise =
       Promise::Resolve(sgo, aCx, JS::UndefinedHandleValue, result);
     if (NS_WARN_IF(result.Failed())) {
+      result.SuppressException();
       return nullptr;
     }
   }
@@ -2140,6 +2142,7 @@ public:
     nsRefPtr<PushEvent> event =
       PushEvent::Constructor(globalObj, NS_LITERAL_STRING("push"), pei, result);
     if (NS_WARN_IF(result.Failed())) {
+      result.SuppressException();
       return false;
     }
 
@@ -3479,6 +3482,7 @@ private:
       ErrorResult result;
       internalHeaders->Set(mHeaderNames[i], mHeaderValues[i], result);
       if (NS_WARN_IF(result.Failed())) {
+        result.SuppressException();
         return false;
       }
     }
@@ -3493,6 +3497,7 @@ private:
     ErrorResult result;
     nsRefPtr<Request> request = Request::Constructor(globalObj, requestInfo, reqInit, result);
     if (NS_WARN_IF(result.Failed())) {
+      result.SuppressException();
       return false;
     }
     // For Telemetry, note that this Request object was created by a Fetch event.
@@ -3514,6 +3519,7 @@ private:
     nsRefPtr<FetchEvent> event =
       FetchEvent::Constructor(globalObj, NS_LITERAL_STRING("fetch"), init, result);
     if (NS_WARN_IF(result.Failed())) {
+      result.SuppressException();
       return false;
     }
 
@@ -3949,6 +3955,7 @@ FireControllerChangeOnDocument(nsIDocument* aDocument)
   ErrorResult result;
   dom::Navigator* navigator = window->GetNavigator(result);
   if (NS_WARN_IF(result.Failed())) {
+    result.SuppressException();
     return;
   }