Fix build warnings in SkAlphaThresholdFilter

gm/imagealphathreshold.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkAlphaThresholdFilter.h"
 #include "SkRandom.h"
@@ skipping 25 matching lines @@
     virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
         SkIRect rects[2];
         rects[0] = SkIRect::MakeXYWH(0, 150, WIDTH, HEIGHT - 300);
         rects[1] = SkIRect::MakeXYWH(150, 0, WIDTH - 300, HEIGHT);
         SkRegion region;
         region.setRects(rects, 2);
 
         SkMatrix matrix;
         matrix.reset();
         matrix.setTranslate(WIDTH * .1f, HEIGHT * .1f);
-        matrix.postScale(.8, .8);
+        matrix.postScale(.8f, .8f);
 
         canvas->concat(matrix);
 
         SkPaint paint;
         paint.setImageFilter(
             SkAlphaThresholdFilter::Create(region, 0.2f, 0.7f))->unref();
         canvas->saveLayer(NULL, &paint);
         paint.setAntiAlias(true);
 
         SkPaint rect_paint;
@@ skipping 16 matching lines @@
 private:
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new ImageAlphaThresholdGM; }
 static GMRegistry reg(MyFactory);
 
 }