[debugger] fix stepping over await calls for ignition generators.

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 "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 1364 matching lines @@
   // Update PCs on the stack to point to recompiled code.
   RedirectActiveFunctions redirect_visitor(*shared);
   redirect_visitor.VisitThread(isolate_, isolate_->thread_local_top());
   isolate_->thread_manager()->IterateArchivedThreads(&redirect_visitor);
 
   return true;
 }
 
 void Debug::RecordAsyncFunction(Handle<JSGeneratorObject> generator_object) {
   if (last_step_action() <= StepOut) return;
+  if (!generator_object->function()->shared()->is_async()) return;
   DCHECK(!has_suspended_generator());
-  DCHECK(generator_object->function()->shared()->is_async());
   thread_local_.suspended_generator_ = *generator_object;
   ClearStepping();
 }
 
 class SharedFunctionInfoFinder {
  public:
   explicit SharedFunctionInfoFinder(int target_position)
       : current_candidate_(NULL),
         current_candidate_closure_(NULL),
         current_start_position_(RelocInfo::kNoPosition),
@@ skipping 1195 matching lines @@
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 }  // namespace internal
 }  // namespace v8