Refactor isolate interrupts to use OOB messages instead of interrupt bits.

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_tools_api.h"
 
 #include "vm/object.h"
@@ skipping 538 matching lines @@
 
   // Utility functions.
   static const char* QualifiedFunctionName(const Function& func);
 
   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();
+  RawError* SignalBpReached();
+  RawError* DebuggerStepCallback();
+  RawError* SignalIsolateInterrupted();
 
   void BreakHere(const String& msg);
 
   void SignalExceptionThrown(const Instance& exc);
   void SignalIsolateEvent(DebuggerEvent::EventType type);
-  static void SignalIsolateInterrupted();
 
   RawCode* GetPatchedStubAddress(uword breakpoint_address);
 
   void PrintBreakpointsToJSONArray(JSONArray* jsarr) const;
   void PrintSettingsToJSONObject(JSONObject* jsobj) const;
 
   static bool IsDebuggable(const Function& func);
 
   intptr_t limitBreakpointId() { return next_id_; }
 
@@ skipping 115 matching lines @@
 
   friend class Isolate;
   friend class BreakpointLocation;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_