[oilpan]: Remove support for tracing off-heap hashmaps.

Source/core/page/PrintContext.cpp

 /*
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2007 Apple Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 363 matching lines @@
         graphicsContext.restore();
 
         currentHeight += pageSizeInPixels.height() + 1;
     }
 
     graphicsContext.restore();
 }
 
 void PrintContext::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_linkedDestinations);
+#endif
 }
 
 }