[DevTools] Fix v8_inspector compilation with node

third_party/WebKit/Source/platform/v8_inspector/public/V8DebuggerClient.h

 // Copyright 2015 The Chromium 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 V8DebuggerClient_h
 #define V8DebuggerClient_h
 
 #include "platform/inspector_protocol/Platform.h"
 #include "platform/v8_inspector/public/V8ConsoleTypes.h"
 #include "platform/v8_inspector/public/V8ContextInfo.h"
 
 #include <v8.h>
 
 namespace blink {
 
+class V8StackTrace;
+
 class PLATFORM_EXPORT V8DebuggerClient {
 public:
     virtual ~V8DebuggerClient() { }
     virtual void runMessageLoopOnPause(int contextGroupId) = 0;
     virtual void quitMessageLoopOnPause() = 0;
     // TODO(dgozman): we don't really need to mute warnings and deprecations.
     virtual void muteWarningsAndDeprecations() = 0;
     virtual void unmuteWarningsAndDeprecations() = 0;
     virtual void beginUserGesture() = 0;
     virtual void endUserGesture() = 0;
@@ skipping 19 matching lines @@
 
     typedef void (*TimerCallback)(void*);
     virtual void startRepeatingTimer(double, TimerCallback, void* data) = 0;
     virtual void cancelTimer(void* data) = 0;
 };
 
 } // namespace blink
 
 
 #endif // V8DebuggerClient_h