[async await] Fix debug async task event

test/mjsunit/harmony/debug-async-function-async-task-event.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --harmony-async-await --expose-debug-as debug --allow-natives-syntax
 
 // The test observes the callbacks that async/await makes to the inspector
 // to make accurate stack traces. The pattern is based on saving a stack once
 // with enqueueRecurring and restoring it multiple times.
 
@@ skipping 25 matching lines @@
   assertTrue(expected.length > 0);
   assertEquals(expected.shift(), msg);
   if (!expected.length) {
     Debug.setListener(null);
   }
 }
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.AsyncTaskEvent) return;
   try {
+    if ("Promise.resolve" == event_data.name()) return;
     if (base_id < 0)
       base_id = event_data.id();
     var id = event_data.id() - base_id + 1;
     assertTrue("async function" == event_data.name());
     assertLog(event_data.type() + " #" + id);
   } catch (e) {
     print(e + e.stack)
     exception = e;
   }
 }
@@ skipping 10 matching lines @@
   assertLog("then #1");
   await undefined;
   assertLog("then #2");
 }
 main();
 resolver();
 
 %RunMicrotasks();
 
 assertNull(exception);
+
+Debug.clearBreakOnUncaughtException();
+Debug.setListener(null);
+
+var resolve;
+var turnOnListenerPromise = new Promise(r => resolve = r);
+async function confused() {
+  await turnOnListenerPromise;
+  throw foo
+}
+
+confused();
+
+Promise.resolve().then(() => {
+  Debug.setListener(listener);
+  Debug.setBreakOnUncaughtException();
+  resolve();
+});
+
+%RunMicrotasks();
+assertNull(exception);