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

src/gpu/effects/GrRRectEffect.cpp

Index: src/gpu/effects/GrRRectEffect.cpp
diff --git a/src/gpu/effects/GrRRectEffect.cpp b/src/gpu/effects/GrRRectEffect.cpp
index 619cd99daf26d37160e5ce4d11b6213c5cf581eb..1bbf2f7976c2371940e544ee46b086a775b08ab9 100644
--- a/src/gpu/effects/GrRRectEffect.cpp
+++ b/src/gpu/effects/GrRRectEffect.cpp
@@ -314,23 +314,23 @@ void GLRRectEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect&
                 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: