Implement debugger support for async step-out

runtime/vm/debugger.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_DEBUGGER_H_
 #define RUNTIME_VM_DEBUGGER_H_
 
 #include "include/dart_tools_api.h"
 
 #include "vm/object.h"
@@ skipping 472 matching lines @@
 
   BreakpointLocation* BreakpointLocationAtLineCol(const String& script_url,
                                                   intptr_t line_number,
                                                   intptr_t column_number);
 
 
   void RemoveBreakpoint(intptr_t bp_id);
   Breakpoint* GetBreakpointById(intptr_t id);
 
   void MaybeAsyncStepInto(const Closure& async_op);
+  void AsyncStepInto(const Closure& async_op);
 
   void Continue();
 
   bool SetResumeAction(ResumeAction action,
                        intptr_t frame_index = 1,
                        const char** error = NULL);
 
   bool IsStepping() const { return resume_action_ != kContinue; }
 
   bool IsSingleStepping() const { return resume_action_ == kStepInto; }
@@ skipping 268 matching lines @@
 
   friend class Isolate;
   friend class BreakpointLocation;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_DEBUGGER_H_