Run HTMLSourceTracker hooks only when XSSAuditor is enabled

Source/core/html/parser/XSSAuditor.h

 /*
  * Copyright (C) 2011 Adam Barth. 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 50 matching lines @@
     XSSAuditor();
 
     void init(Document*, XSSAuditorDelegate*);
     void initForFragment();
 
     PassOwnPtr<XSSInfo> filterToken(const FilterTokenRequest&);
     bool isSafeToSendToAnotherThread() const;
 
     void setEncoding(const WTF::TextEncoding&);
 
+    bool isEnabled() const { return m_isEnabled; }
+
 private:
     static const size_t kMaximumFragmentLengthTarget = 100;
 
     enum State {
         Uninitialized,
         FilteringTokens,
         PermittingAdjacentCharacterTokens,
         SuppressingAdjacentCharacterTokens
     };
 
@@ skipping 51 matching lines @@
 
     State m_state;
     bool m_scriptTagFoundInRequest;
     unsigned m_scriptTagNestingLevel;
     WTF::TextEncoding m_encoding;
 };
 
 }
 
 #endif