Allow stepping into Promise handlers.

test/mjsunit/es6/debug-stepin-promises.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: --allow-natives-syntax --expose-debug-as debug
+
+Debug = debug.Debug
+var exception = null;
+var break_count = 0;

[arv (Not doing code reviews), 2014/11/18 18:51:08]

no underscores in js

+var expected_breaks = 7;
+
+function listener(event, exec_state, event_data, data) {
+  try {
+    if (event == Debug.DebugEvent.Break) {
+      assertTrue(exec_state.frameCount() != 0, "FAIL: Empty stack trace");
+      var source = exec_state.frame(0).sourceLineText();
+      print("paused at: " + source);
+      assertTrue(source.indexOf("// Break " + break_count + ".") > 0,
+                 "Unexpected pause at: " + source);
+      if (source.indexOf("StepOver.") !== -1) {
+        exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+      } else {
+        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+      }
+      ++break_count;
+    } else if (event == Debug.DebugEvent.AsyncTaskEvent &&
+               event_data.type() === "willHandle" &&
+               event_data.name() !== "Object.observe" &&
+               break_count > 0) {
+      exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    }
+  } catch (e) {
+    exception = e;
+    print(e, e.stack);
+  }
+};
+
+Debug.setListener(listener);
+
+Promise.resolve(42)
+  .then(promise1)
+  .then(Object) // Should skip stepping into native.
+  .then(Boolean) // Should skip stepping into native.
+  .then(promise2)
+  .then(undefined, promise3)

[arv (Not doing code reviews), 2014/11/18 18:51:08]

or

.catch(promise3)

+  .catch(function(e) {
+    %AbortJS("FAIL: uncaught exception " + e);
+  });
+
+function promise1()
+{

[arv (Not doing code reviews), 2014/11/18 18:51:08]

{ on previous line

[aandrey, 2014/11/19 11:41:27]

Addressed in https://codereview.chromium.org/739523002/

+  debugger; // Break 0.
+  return exception || 1; // Break 1.
+} // Break 2.
+
+function promise2()
+{
+  throw new Error; // Break 3.
+}
+
+function promise3()
+{
+  finalize(); // Break 4. StepOver.
+  return break_count; // Break 5.
+} // Break 6.
+
+function finalize()
+{
+  var dummy = {};
+  Object.observe(dummy, function() {
+    if (expected_breaks !== break_count) {
+      %AbortJS("FAIL: expected <" + expected_breaks + "> breaks instead of <" +
+               break_count + ">");
+    }
+    if (exception !== null) {
+      %AbortJS("FAIL: exception: " + exception);
+    }
+  });
+  dummy.foo = 1;
+}