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

test/mjsunit/es6/debug-promises-throw-in-reject.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 debug events when an exception is thrown inside a Promise, which is
 // caught by a custom promise, which throws a new exception in its reject
-// handler.  We expect a PendingExceptionInPromise event to be triggered.
+// handler.  We expect an Exception debug event with a promise to be triggered.
 
 Debug = debug.Debug;
 
 var log = [];
 var step = 0;
 
 var p = new Promise(function(resolve, reject) {
   log.push("resolve");
   resolve();
 });
 
 function MyPromise(resolver) {
   var reject = function() {
     log.push("throw reject");
-    throw new Error("reject");
+    throw new Error("reject");  // event
   };
   var resolve = function() { };
   log.push("construct");
   resolver(resolve, reject);
 };
 
 MyPromise.prototype = p;
 p.constructor = MyPromise;
 
 var q = p.chain(
   function() {
     log.push("throw caught");
     throw new Error("caught");
   });
 
 function listener(event, exec_state, event_data, data) {
   try {
-    if (event == Debug.DebugEvent.PendingExceptionInPromise) {
+    if (event == Debug.DebugEvent.Exception) {
       assertEquals(["resolve", "construct", "end main",
                     "throw caught", "throw reject"], log);
-      assertEquals("caught", event_data.exception().message);
-    } else if (event == Debug.DebugEvent.Exception) {
-      assertUnreachable();
+      assertEquals("reject", event_data.exception().message);
+      assertEquals(q, event_data.promise());
+      assertTrue(exec_state.frame(0).sourceLineText().indexOf('// event') > 0);
     }
   } catch (e) {
     // Signal a failure with exit code 1.  This is necessary since the
     // debugger swallows exceptions and we expect the chained function
     // and this listener to be executed after the main script is finished.
     print("Unexpected exception: " + e + "\n" + e.stack);
     quit(1);
   }
 }
 
 Debug.setBreakOnUncaughtException();
 Debug.setListener(listener);
 
 log.push("end main");