Add 'dart:debugger' library

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 424 matching lines @@
 
   RawObject* GetInstanceField(const Class& cls,
                               const String& field_name,
                               const Instance& object);
   RawObject* GetStaticField(const Class& cls,
                             const String& field_name);
 
   void SignalBpReached();
   void DebuggerStepCallback();
 
+  void ExplicitBreakpoint();
+
   void SignalExceptionThrown(const Instance& exc);
   void SignalIsolateEvent(DebuggerEvent::EventType type);
   static void SignalIsolateInterrupted();
 
   uword GetPatchedStubAddress(uword breakpoint_address);
 
   void PrintBreakpointsToJSONArray(JSONArray* jsarr) const;
 
   static bool IsDebuggable(const Function& func);
 
@@ skipping 109 matching lines @@
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_