Switch arguments to const Length references for performance

Source/core/rendering/RenderBoxModelObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 404 matching lines @@
 int RenderBoxModelObject::pixelSnappedOffsetWidth() const
 {
     return snapSizeToPixel(offsetWidth(), offsetLeft());
 }
 
 int RenderBoxModelObject::pixelSnappedOffsetHeight() const
 {
     return snapSizeToPixel(offsetHeight(), offsetTop());
 }
 
-LayoutUnit RenderBoxModelObject::computedCSSPadding(Length padding) const
+LayoutUnit RenderBoxModelObject::computedCSSPadding(const Length& padding) const
 {
     LayoutUnit w = 0;
     if (padding.isPercent())
         w = containingBlockLogicalWidthForContent();
     return minimumValueForLength(padding, w);
 }
 
 RoundedRect RenderBoxModelObject::getBackgroundRoundedRect(const LayoutRect& borderRect, InlineFlowBox* box, LayoutUnit inlineBoxWidth, LayoutUnit inlineBoxHeight,
     bool includeLogicalLeftEdge, bool includeLogicalRightEdge) const
 {
@@ skipping 2400 matching lines @@
     ASSERT(!beforeChild || toBoxModelObject == beforeChild->parent());
     for (RenderObject* child = startChild; child && child != endChild; ) {
         // Save our next sibling as moveChildTo will clear it.
         RenderObject* nextSibling = child->nextSibling();
         moveChildTo(toBoxModelObject, child, beforeChild, fullRemoveInsert);
         child = nextSibling;
     }
 }
 
 } // namespace WebCore