Fix radical assumption that 0.5 in double is exactly convertible to float.

src/gpu/effects/GrRRectEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrRRectEffect.h"
 
 #include "gl/GrGLEffect.h"
@@ skipping 296 matching lines @@
                 break;
             case RRectEffect::kTopLeft_CornerFlag:
                 radius = rrect.radii(SkRRect::kUpperLeft_Corner).fX;
                 rect.fLeft += radius;
                 rect.fTop += radius;
                 rect.fRight += 0.5f;
                 rect.fBottom += 0.5f;
                 break;
             case RRectEffect::kTopRight_CornerFlag:
                 radius = rrect.radii(SkRRect::kUpperRight_Corner).fX;
-                rect.fLeft -= 0.5;
+                rect.fLeft -= 0.5f;
                 rect.fTop += radius;
                 rect.fRight -= radius;
                 rect.fBottom += 0.5f;
                 break;
             case RRectEffect::kBottomRight_CornerFlag:
                 radius = rrect.radii(SkRRect::kLowerRight_Corner).fX;
-                rect.fLeft -= 0.5;
-                rect.fTop -= 0.5;
+                rect.fLeft -= 0.5f;
+                rect.fTop -= 0.5f;
                 rect.fRight -= radius;
                 rect.fBottom -= radius;
                 break;
             case RRectEffect::kBottomLeft_CornerFlag:
                 radius = rrect.radii(SkRRect::kLowerLeft_Corner).fX;
                 rect.fLeft += radius;
-                rect.fTop -= 0.5;
-                rect.fRight += 0.5;
+                rect.fTop -= 0.5f;
+                rect.fRight += 0.5f;
                 rect.fBottom -= radius;
                 break;
             case RRectEffect::kLeft_CornerFlags:
                 radius = rrect.radii(SkRRect::kUpperLeft_Corner).fX;
                 rect.fLeft += radius;
                 rect.fTop += radius;
                 rect.fRight += 0.5f;
                 rect.fBottom -= radius;
                 break;
             case RRectEffect::kTop_CornerFlags:
@@ skipping 77 matching lines @@
             case RRectEffect::kAll_CornerFlags:
                 break;
             default:
                 return NULL;
         }
     } else {
         return NULL;
     }
     return RRectEffect::Create(edgeType, cornerFlags, rrect);
 }