Oilpan: fix build after r198789.

Source/core/inspector/InspectorDebuggerAgent.cpp

 /*
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 1716 matching lines @@
 
 void InspectorDebuggerAgent::resetModifiedSources()
 {
     m_editedScripts.clear();
 }
 
 DEFINE_TRACE(InspectorDebuggerAgent)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_injectedScriptManager);
+    visitor->trace(m_debugger);
     visitor->trace(m_listener);
     visitor->trace(m_v8AsyncCallTracker);
     visitor->trace(m_promiseTracker);
     visitor->trace(m_asyncOperations);
     visitor->trace(m_currentAsyncCallChain);
     visitor->trace(m_asyncCallTrackingListeners);
 #endif
     InspectorBaseAgent::trace(visitor);
 }
 
 PassRefPtr<TypeBuilder::Debugger::ExceptionDetails> InspectorDebuggerAgent::createExceptionDetails(v8::Isolate* isolate, v8::Local<v8::Message> message)
 {
     RefPtr<ExceptionDetails> exceptionDetails = ExceptionDetails::create().setText(toCoreStringWithUndefinedOrNullCheck(message->Get()));
     exceptionDetails->setLine(message->GetLineNumber());
     exceptionDetails->setColumn(message->GetStartColumn());
     v8::Local<v8::StackTrace> messageStackTrace = message->GetStackTrace();
     if (!messageStackTrace.IsEmpty() && messageStackTrace->GetFrameCount() > 0)
         exceptionDetails->setStackTrace(createScriptCallStack(isolate, messageStackTrace, messageStackTrace->GetFrameCount())->buildInspectorArray());
     return exceptionDetails.release();
 }
 
 } // namespace blink