Handle a terminating context in messageHandlerinWorker().

If execution is terminated while constructing the ErrorEvent representing
the incoming v8::Message, do not attempt to report the exception.

R=haraken@chromium.org
BUG=393273

Review URL: https://codereview.chromium.org/405933002

git-svn-id: svn://svn.chromium.org/blink/trunk@178929 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/bindings/core/v8/V8Initializer.cpp

@@ -226,8 +226,12 @@ static void messageHandlerInWorker(v8::Handle<v8::Message> message, v8::Handle<v
         RefPtrWillBeRawPtr<ErrorEvent> event = ErrorEvent::create(errorMessage, sourceURL, message->GetLineNumber(), message->GetStartColumn() + 1, &DOMWrapperWorld::current(isolate));
         AccessControlStatus corsStatus = message->IsSharedCrossOrigin() ? SharableCrossOrigin : NotSharableCrossOrigin;
 
-        V8ErrorHandler::storeExceptionOnErrorEventWrapper(event.get(), data, scriptState->context()->Global(), isolate);
-        context->reportException(event.release(), nullptr, corsStatus);
+        // If execution termination has been triggered as part of constructing
+        // the error event from the v8::Message, quietly leave.
+        if (!v8::V8::IsExecutionTerminating(isolate)) {
+            V8ErrorHandler::storeExceptionOnErrorEventWrapper(event.get(), data, scriptState->context()->Global(), isolate);
+            context->reportException(event.release(), nullptr, corsStatus);
+        }
     }
 
     isReportingException = false;