[inspector] improved V8Debugger::breakProgram method

test/inspector/debugger/destory-in-break-program.js

+// Copyright 2017 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.
+
+InspectorTest.log('Check destroying agent inside of breakProgram');
+
+(async function test(){
+  await Protocol.Debugger.enable();
+  Protocol.Runtime.evaluate({expression: 'inspector.breakProgram(\'\', \'{}\')'});
+  await Protocol.Debugger.oncePaused();
+  utils.disconnect();
+  utils.quit();
+})();