Introduce more debug events for promises.

test/mjsunit/es6/debug-promises-update-parent-event.js

+// Copyright 2014 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: --expose-debug-as debug
+
+Debug = debug.Debug;
+
+var exception = null;
+var promise, parentPromise;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.PromiseEvent) return;
+  try {
+    if (event_data instanceof debug.UpdatePromiseParentEvent) {
+      assertTrue(event_data.promise().isPromise());
+      promise = event_data.promise().value();
+
+      assertTrue(event_data.parentPromise().isPromise());
+      parentPromise = event_data.parentPromise().value();
+    }
+  } catch (e) {
+    print(e + e.stack);
+    exception = e;
+  }
+}
+
+Debug.setListener(listener);
+
+var p1 = new Promise(function(resolve, reject) { resolve(1) });
+var p2 = p1.then().then();
+var p3 = p2.then();
+assertSame(parentPromise, p2);
+assertSame(promise, p3);
+
+assertNull(exception);
+Debug.setListener(null);