Reland "Trigger exception debug event for promises at the throw site."

test/mjsunit/es6/debug-promises-reentry.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: --harmony-promises --expose-debug-as debug
+
+// Test reentry of special try catch for Promises.
+
+Debug = debug.Debug;
+
+Debug.setBreakOnUncaughtException();
+Debug.setListener(function(event, exec_state, event_data, data) { });
+
+var p = new Promise(function(resolve, reject) { resolve(); });
+var q = p.chain(function() {
+  new Promise(function(resolve, reject) { resolve(); });
+});