Simplify application of perspective origin.

Source/core/paint/DeprecatedPaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 890 matching lines @@
 
 TransformationMatrix DeprecatedPaintLayer::perspectiveTransform() const
 {
     if (!layoutObject()->hasTransformRelatedProperty())
         return TransformationMatrix();
 
     const ComputedStyle& style = layoutObject()->styleRef();
     if (!style.hasPerspective())
         return TransformationMatrix();
 
-    // Maybe fetch the perspective from the backing?
-    const IntRect borderBox = toLayoutBox(layoutObject())->pixelSnappedBorderBoxRect();
-    const float boxWidth = borderBox.width();
-    const float boxHeight = borderBox.height();
-
-    float perspectiveOriginX = floatValueForLength(style.perspectiveOriginX(), boxWidth);
-    float perspectiveOriginY = floatValueForLength(style.perspectiveOriginY(), boxHeight);
-
-    // A perspective origin of 0,0 makes the vanishing point in the center of the element.
-    // We want it to be in the top-left, so subtract half the height and width.
-    perspectiveOriginX -= boxWidth / 2.0f;
-    perspectiveOriginY -= boxHeight / 2.0f;
-
     TransformationMatrix t;
-    t.translate(perspectiveOriginX, perspectiveOriginY);
     t.applyPerspective(style.perspective());
-    t.translate(-perspectiveOriginX, -perspectiveOriginY);
-
     return t;
 }
 
 FloatPoint DeprecatedPaintLayer::perspectiveOrigin() const
 {
     if (!layoutObject()->hasTransformRelatedProperty())
         return FloatPoint();
 
     const LayoutRect borderBox = toLayoutBox(layoutObject())->borderBoxRect();
     const ComputedStyle& style = layoutObject()->styleRef();
@@ skipping 2029 matching lines @@
     }
 }
 
 void showLayerTree(const blink::LayoutObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif