[inspector] Refactor protocol-test.js

test/inspector/debugger/max-async-call-chain-depth.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.
+
 // TODO(kozyatinskiy): fix or remove it later.
-InspectorTest.log('Checks that we trim async call chains correctly.');
+let {session, contextGroup, Protocol} = InspectorTest.start('Checks that we trim async call chains correctly.');
 
 Protocol.Debugger.enable();
 InspectorTest.log('set async chain depth to 8');
 Protocol.Debugger.setAsyncCallStackDepth({maxDepth: 8});
 InspectorTest.runAsyncTestSuite([
   async function testDebuggerPaused() {
     runWithAsyncChain(4, 'debugger;');
     dumpAsyncChainLength(await Protocol.Debugger.oncePaused());
     await Protocol.Debugger.resume();
 
@@ skipping 136 matching lines @@
 
 function dumpAsyncChainLength(message) {
   let stackTrace = message.params.asyncStackTrace || message.params.stackTrace.parent;
   let asyncChainCount = 0;
   while (stackTrace) {
     ++asyncChainCount;
     stackTrace = stackTrace.parent;
   }
   InspectorTest.log(`actual async chain len: ${asyncChainCount}`);
 }