Improve computation of ctmScale{X,Y} in NativeImageSkia::drawPattern

Source/platform/graphics/skia/NativeImageSkia.cpp

 /*
  * Copyright (c) 2008, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 433 matching lines @@
     const FloatRect& destRect,
     blink::WebBlendMode blendMode,
     const IntSize& repeatSpacing) const
 {
     FloatRect normSrcRect = floatSrcRect;
     normSrcRect.intersect(FloatRect(0, 0, bitmap().width(), bitmap().height()));
     if (destRect.isEmpty() || normSrcRect.isEmpty())
         return; // nothing to draw
 
     SkMatrix totalMatrix = context->getTotalMatrix();
-    SkScalar ctmScaleX = totalMatrix.getScaleX();
-    SkScalar ctmScaleY = totalMatrix.getScaleY();
+    AffineTransform ctm = context->getCTM();
+    SkScalar ctmScaleX = ctm.xScale();
+    SkScalar ctmScaleY = ctm.yScale();
     totalMatrix.preScale(scale.width(), scale.height());
 
     // Figure out what size the bitmap will be in the destination. The
     // destination rect is the bounds of the pattern, we need to use the
     // matrix to see how big it will be.
     SkRect destRectTarget;
     totalMatrix.mapRect(&destRectTarget, normSrcRect);
 
     float destBitmapWidth = SkScalarToFloat(destRectTarget.width());
     float destBitmapHeight = SkScalarToFloat(destRectTarget.height());
@@ skipping 144 matching lines @@
 SkIRect NativeImageSkia::ImageResourceInfo::rectInSubset(const SkIRect& otherScaledImageSubset)
 {
     if (!scaledImageSubset.contains(otherScaledImageSubset))
         return SkIRect::MakeEmpty();
     SkIRect subsetRect = otherScaledImageSubset;
     subsetRect.offset(-scaledImageSubset.x(), -scaledImageSubset.y());
     return subsetRect;
 }
 
 } // namespace WebCore