[debugger] Further stepping support in test wrapper

test/mjsunit/debug-evaluate-modify-this.js

-// Copyright 2016 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 f = () => { debugger; }
-var g = function() { debugger; }
-var h = (function() { return () => { debugger; }; }).call({});
-
-function listener(event, exec_state, event_data, data) {
-  if (event != Debug.DebugEvent.Break) return;
-  try {
-    assertThrows(() => exec_state.frame(0).evaluate("this = 2"));
-  } catch (e) {
-    exception = e;
-    print("Caught something. " + e + " " + e.stack);
-  };
-};
-
-Debug.setListener(listener);
-
-f();
-g();
-g.call({});
-h();
-
-Debug.setListener(null);
-assertNull(exception);