Make return statements single steppable

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 VM_DEBUGGER_H_
 #define VM_DEBUGGER_H_
 
 #include "include/dart_debugger_api.h"
 
 #include "vm/object.h"
@@ skipping 84 matching lines @@
 
   SourceBreakpoint* src_bpt() const { return src_bpt_; }
   void set_src_bpt(SourceBreakpoint* value) { src_bpt_ = value; }
 
   void set_next(CodeBreakpoint* value) { next_ = value; }
   CodeBreakpoint* next() const { return this->next_; }
   intptr_t pc_desc_index() const { return pc_desc_index_; }
 
   void PatchCode();
   void RestoreCode();
-  void PatchFunctionReturn();
-  void RestoreFunctionReturn();
 
   RawFunction* function_;
   intptr_t pc_desc_index_;
   intptr_t token_pos_;
   uword pc_;
   intptr_t line_number_;
   bool is_enabled_;
 
   SourceBreakpoint* src_bpt_;
   CodeBreakpoint* next_;
@@ skipping 358 matching lines @@
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_