change mapRectScaleTranslate to pass args/ret by value

tests/MatrixTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMath.h"
 #include "SkMatrix.h"
 #include "SkMatrixUtils.h"
@@ skipping 960 matching lines @@
     for (int i = 0; i < 10000; ++i) {
         SkRect src = SkRect::MakeLTRB(rand.nextSScalar1() * scale,
                                       rand.nextSScalar1() * scale,
                                       rand.nextSScalar1() * scale,
                                       rand.nextSScalar1() * scale);
         SkRect dst[3];
         
         mat.mapPoints((SkPoint*)&dst[0].fLeft, (SkPoint*)&src.fLeft, 2);
         dst[0].sort();
         mat.mapRect(&dst[1], src);
-        mat.mapRectScaleTranslate(&dst[2], src);
+        dst[2] = mat.mapRectScaleTranslate(src);
 
         REPORTER_ASSERT(r, dst[0] == dst[1]);
         REPORTER_ASSERT(r, dst[0] == dst[2]);
     }
 }