Add a src rect to drawImageLattice() API

src/core/SkLatticeIter.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLatticeIter_DEFINED
 #define SkLatticeIter_DEFINED
 
 #include "SkCanvas.h"
 #include "SkScalar.h"
 #include "SkTArray.h"
 
 struct SkIRect;
 struct SkRect;
 
 /**
  *  Disect a lattice request into an sequence of src-rect / dst-rect pairs
  */
 class SkLatticeIter {
 public:
 
     static bool Valid(int imageWidth, int imageHeight, const SkCanvas::Lattice& lattice);
 
-    SkLatticeIter(int imageWidth, int imageHeight, const SkCanvas::Lattice& lattice,
-                  const SkRect& dst);
+    SkLatticeIter(const SkCanvas::Lattice& lattice, const SkRect& dst);
 
     static bool Valid(int imageWidth, int imageHeight, const SkIRect& center);
 
     SkLatticeIter(int imageWidth, int imageHeight, const SkIRect& center, const SkRect& dst);
 
     /**
      *  While it returns true, use src/dst to draw the image/bitmap
      */
     bool next(SkRect* src, SkRect* dst);
 
@@ skipping 16 matching lines @@
     SkTArray<SkScalar> fDstY;
     SkTArray<SkCanvas::Lattice::Flags> fFlags;
 
     int  fCurrX;
     int  fCurrY;
     int  fNumRectsInLattice;
     int  fNumRectsToDraw;
 };
 
 #endif