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

test/mjsunit/es6/debug-promises-uncaught-all.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 we listen to all exceptions and
 // there is a catch handler for the exception thrown in a Promise.
-// Expectation:
-//  - the normal Exception debug event is triggered.
-//  - the PendingExceptionInPromise debug event is triggered afterwards,
-//    with the same exception object.
+// We expect an Exception debug event with a promise to be triggered.
 
 Debug = debug.Debug;
 
 var log = [];
 var step = 0;
 var exception = undefined;
 
 var p = new Promise(function(resolve, reject) {
   log.push("resolve");
   resolve();
 });
 
 var q = p.chain(
   function() {
     log.push("throw");
-    throw new Error("uncaught");
+    throw new Error("uncaught");  // event
   });
 
 function listener(event, exec_state, event_data, data) {
   try {
     // Ignore exceptions during startup in stress runs.
-    if (step > 1) return;
+    if (step >= 1) return;
     assertEquals(["resolve", "end main", "throw"], log);
     if (event == Debug.DebugEvent.Exception) {
       assertEquals(0, step);
-      exception = event_data.exception();
-      assertEquals(undefined, event_data.promise());
-    } else if (event == Debug.DebugEvent.PendingExceptionInPromise) {
-      assertEquals(1, step);
-      assertEquals(exception, event_data.exception());
-      assertEquals("uncaught", exception.message);
+      assertEquals("uncaught", event_data.exception().message);
       assertTrue(event_data.promise() instanceof Promise);
+      assertEquals(q, event_data.promise());
       assertTrue(event_data.uncaught());
-    } else {
-      return;
+      // Assert that the debug event is triggered at the throw site.
+      assertTrue(exec_state.frame(0).sourceLineText().indexOf("// event") > 0);
+      step++;
     }
-    step++;
   } 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.setBreakOnException();
 Debug.setListener(listener);
 
 log.push("end main");