[debugger] step-next across yield should not leave the generator.

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 1412 matching lines @@
       Handle<DebugInfo> debug_info(candidates[i]->GetDebugInfo());
       FindBreakablePositions(debug_info, start_position, end_position,
                              STATEMENT_ALIGNED, positions);
     }
     return true;
   }
   UNREACHABLE();
   return false;
 }
 
-void Debug::RecordAsyncFunction(Handle<JSGeneratorObject> generator_object) {
+void Debug::RecordGenerator(Handle<JSGeneratorObject> generator_object) {
   if (last_step_action() <= StepOut) return;
-  if (!IsAsyncFunction(generator_object->function()->shared()->kind())) return;
+
+  if (last_step_action() == StepNext) {
+    // Only consider this generator a step-next target if not stepping in.
+    JavaScriptFrameIterator stack_iterator(isolate_);
+    JavaScriptFrame* frame = stack_iterator.frame();
+    if (frame->UnpaddedFP() < thread_local_.target_fp_) return;
+  }
+
   DCHECK(!has_suspended_generator());
   thread_local_.suspended_generator_ = *generator_object;
   ClearStepping();
 }
 
 class SharedFunctionInfoFinder {
  public:
   explicit SharedFunctionInfoFinder(int target_position)
       : current_candidate_(NULL),
         current_candidate_closure_(NULL),
@@ skipping 1171 matching lines @@
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 }  // namespace internal
 }  // namespace v8