Decouple root visitors from object visitors.

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/assembler.h"
 #include "src/base/atomicops.h"
@@ skipping 347 matching lines @@
   // Support for LiveEdit
   void ScheduleFrameRestart(StackFrame* frame);
 
   bool AllFramesOnStackAreBlackboxed();
 
   // Threading support.
   char* ArchiveDebug(char* to);
   char* RestoreDebug(char* from);
   static int ArchiveSpacePerThread();
   void FreeThreadResources() { }
-  void Iterate(ObjectVisitor* v);
+  void Iterate(RootVisitor* v);
 
   bool CheckExecutionState(int id) {
     return CheckExecutionState() && break_id() == id;
   }
 
   bool CheckExecutionState() {
     return is_active() && !debug_context().is_null() && break_id() != 0;
   }
 
   bool PerformSideEffectCheck(Handle<JSFunction> function);
@@ skipping 428 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_