first step to remove unsafe handles

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index 4d9504f0d45c9656c9e52b3c58a7b83d9521774d..37972ea3c88d9b70da2bc954d0416756f5da1cab 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -292,8 +292,10 @@ class Shell : public i::AllStatic {
   static void MapCounters(const char* name);
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
-  static Handle<Object> DebugMessageDetails(Handle<String> message);
-  static Handle<Value> DebugCommandToJSONRequest(Handle<String> command);
+  static Handle<Object> DebugMessageDetails(Isolate* isolate,
+                                            Handle<String> message);
+  static Handle<Value> DebugCommandToJSONRequest(Isolate* isolate,
+                                                 Handle<String> command);
   static void DispatchDebugMessages();
 #endif  // ENABLE_DEBUGGER_SUPPORT
 #endif  // V8_SHARED