Switch arguments to const Length references for performance

Source/platform/LengthPoint.h

 /*
  * Copyright (c) 2013, Opera Software ASA. 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 22 matching lines @@
 #include "platform/Length.h"
 
 namespace WebCore {
 
 struct LengthPoint {
 public:
     LengthPoint()
     {
     }
 
-    LengthPoint(Length x, Length y)
+    LengthPoint(const Length& x, const Length& y)
         : m_x(x)
         , m_y(y)
     {
     }
 
     bool operator==(const LengthPoint& o) const { return m_x == o.m_x && m_y == o.m_y; }
     bool operator!=(const LengthPoint& o) const { return m_x != o.m_x || m_y != o.m_y; }
 
-    void setX(Length x) { m_x = x; }
-    Length x() const { return m_x; }
+    void setX(const Length& x) { m_x = x; }
+    const Length& x() const { return m_x; }
 
-    void setY(Length y) { m_y = y; }
-    Length y() const { return m_y; }
+    void setY(const Length& y) { m_y = y; }
+    const Length& y() const { return m_y; }
 
 private:
     Length m_x;
     Length m_y;
 };
 
 } // namespace WebCore
 
 #endif // LengthPoint_h