[inspector] introduced stepIntoAsync for chained callbacks

src/debug/debug.cc

 // Copyright 2012 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.
 
 #include "src/debug/debug.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/arguments.h"
@@ skipping 1909 matching lines @@
   info.SetSecondPassCallback(&SendAsyncTaskEventCancel);
 }
 
 // In an async function, reuse the existing stack related to the outer
 // Promise. Otherwise, e.g. in a direct call to then, save a new stack.
 // Promises with multiple reactions with one or more of them being async
 // functions will not get a good stack trace, as async functions require
 // different stacks from direct Promise use, but we save and restore a
 // stack once for all reactions.
 //
-// If this isn't a case of async function, we return false, otherwise
-// we set the correct id and return true.
-//
 // TODO(littledan): Improve this case.
 int GetReferenceAsyncTaskId(Isolate* isolate, Handle<JSPromise> promise) {
   Handle<Symbol> handled_by_symbol =
       isolate->factory()->promise_handled_by_symbol();
   Handle<Object> handled_by_promise =
       JSObject::GetDataProperty(promise, handled_by_symbol);
   if (!handled_by_promise->IsJSPromise()) {
     return isolate->debug()->NextAsyncTaskId(promise);
   }
   Handle<JSPromise> handled_by_promise_js =
@@ skipping 484 matching lines @@
   return v8::Utils::ToLocal(callback_data_);
 }
 
 
 v8::Isolate* EventDetailsImpl::GetIsolate() const {
   return reinterpret_cast<v8::Isolate*>(exec_state_->GetIsolate());
 }
 
 }  // namespace internal
 }  // namespace v8