Fix GLSL int to float error in arc code in GrOvalRenderer.

src/gpu/GrOvalRenderer.cpp

Index: src/gpu/GrOvalRenderer.cpp
diff --git a/src/gpu/GrOvalRenderer.cpp b/src/gpu/GrOvalRenderer.cpp
index ff8790580cceb1b4c88fb161fa3f0f9d6a2d9af4..c57edc9fc0c54f95c342aebcdd0484886da650d1 100644
--- a/src/gpu/GrOvalRenderer.cpp
+++ b/src/gpu/GrOvalRenderer.cpp
@@ -190,7 +190,7 @@ private:
                     fragBuilder->codeAppend("clip *= clamp(circleEdge.z * dot(circleEdge.xy, isectPlane.xy) + isectPlane.z, 0.0, 1.0);");
                 }
                 if (cgp.fInUnionPlane) {
-                    fragBuilder->codeAppend("clip += (1-clip)*clamp(circleEdge.z * dot(circleEdge.xy, unionPlane.xy) + unionPlane.z, 0.0, 1.0);");
+                    fragBuilder->codeAppend("clip += (1.0 - clip)*clamp(circleEdge.z * dot(circleEdge.xy, unionPlane.xy) + unionPlane.z, 0.0, 1.0);");
                 }
                 fragBuilder->codeAppend("edgeAlpha *= clip;");
             }