Make ScriptStreamer and dependents Oilpan friendly.

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 299 matching lines @@
 {
     if (consoleMessage->type() == AssertMessageType && scriptDebugServer().pauseOnExceptionsState() != ScriptDebugServer::DontPauseOnExceptions)
         breakProgram(InspectorFrontend::Debugger::Reason::Assert, nullptr);
 }
 
 String InspectorDebuggerAgent::preprocessEventListener(LocalFrame* frame, const String& source, const String& url, const String& functionName)
 {
     return scriptDebugServer().preprocessEventListener(frame, source, url, functionName);
 }
 
-PassOwnPtr<ScriptSourceCode> InspectorDebuggerAgent::preprocess(LocalFrame* frame, const ScriptSourceCode& sourceCode)
+Nullable<ScriptSourceCode> InspectorDebuggerAgent::preprocess(LocalFrame* frame, const ScriptSourceCode& sourceCode)
 {
     return scriptDebugServer().preprocess(frame, sourceCode);
 }
 
 static PassRefPtr<JSONObject> buildObjectForBreakpointCookie(const String& url, int lineNumber, int columnNumber, const String& condition, bool isRegex)
 {
     RefPtr<JSONObject> breakpointObject = JSONObject::create();
     breakpointObject->setString(DebuggerAgentState::url, url);
     breakpointObject->setNumber(DebuggerAgentState::lineNumber, lineNumber);
     breakpointObject->setNumber(DebuggerAgentState::columnNumber, columnNumber);
@@ skipping 1227 matching lines @@
     visitor->trace(m_v8AsyncCallTracker);
     visitor->trace(m_promiseTracker);
     visitor->trace(m_asyncOperationsForStepInto);
     visitor->trace(m_currentAsyncCallChain);
     visitor->trace(m_asyncCallTrackingListeners);
 #endif
     InspectorBaseAgent::trace(visitor);
 }
 
 } // namespace blink