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

src/debug/debug.h

 // 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.
 
 #ifndef V8_DEBUG_DEBUG_H_
 #define V8_DEBUG_DEBUG_H_
 
 #include "src/allocation.h"
 #include "src/arguments.h"
 #include "src/assembler.h"
@@ skipping 446 matching lines @@
   void PrepareStepIn(Handle<JSFunction> function);
   void PrepareStepInSuspendedGenerator();
   void PrepareStepOnThrow();
   void ClearStepping();
   void ClearStepOut();
 
   bool PrepareFunctionForBreakPoints(Handle<SharedFunctionInfo> shared);
   bool GetPossibleBreakpoints(Handle<Script> script, int start_position,
                               int end_position, std::set<int>* positions);
 
-  void RecordAsyncFunction(Handle<JSGeneratorObject> generator_object);
+  void RecordGenerator(Handle<JSGeneratorObject> generator_object);
 
   // Returns whether the operation succeeded. Compilation can only be triggered
   // if a valid closure is passed as the second argument, otherwise the shared
   // function needs to be compiled already.
   bool EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
                        Handle<JSFunction> function);
   void CreateDebugInfo(Handle<SharedFunctionInfo> shared);
   static Handle<DebugInfo> GetDebugInfo(Handle<SharedFunctionInfo> shared);
 
   template <typename C>
@@ skipping 348 matching lines @@
                                   Handle<Code> code);
   static bool DebugBreakSlotIsPatched(Address pc);
   static void ClearDebugBreakSlot(Isolate* isolate, Address pc);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_DEBUG_DEBUG_H_