Touch.identifier should be long, not unsigned long

Source/platform/PlatformTouchPoint.h

 /*
     Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
 
     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,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 25 matching lines @@
     };
 
     // This is necessary for us to be able to build synthetic events.
     PlatformTouchPoint()
         : m_id(0)
         , m_rotationAngle(0)
         , m_force(0)
     {
     }
 
-    unsigned id() const { return m_id; }
+    int id() const { return m_id; }
     State state() const { return m_state; }
     FloatPoint screenPos() const { return m_screenPos; }
     FloatPoint pos() const { return m_pos; }
     FloatSize radius() const { return m_radius; }
     float rotationAngle() const { return m_rotationAngle; }
     float force() const { return m_force; }
 
 protected:
-    unsigned m_id;
+    int m_id;
     State m_state;
     FloatPoint m_screenPos;
     FloatPoint m_pos;
     FloatSize m_radius;
     float m_rotationAngle;
     float m_force;
 };
 
 }
 
 #endif // PlatformTouchPoint_h