Fix int to float bug in shader on gpu Dotted Line cl

src/gpu/effects/GrDashingEffect.cpp

Index: src/gpu/effects/GrDashingEffect.cpp
diff --git a/src/gpu/effects/GrDashingEffect.cpp b/src/gpu/effects/GrDashingEffect.cpp
index 49169f1051a45eddc277c066c1ca4190f3bcbc08..e46cc040c7fcfed7a206e43e5fc277f1fd5d4728 100644
--- a/src/gpu/effects/GrDashingEffect.cpp
+++ b/src/gpu/effects/GrDashingEffect.cpp
@@ -526,7 +526,7 @@ void GLDashingCircleEffect::emitCode(GrGLFullShaderBuilder* builder,
     builder->fsCodeAppend("\t\tfloat dist = length(center - fragPosShifted);\n");
     if (GrEffectEdgeTypeIsAA(dce.getEdgeType())) {
         builder->fsCodeAppendf("\t\tfloat diff = dist - %s.x;\n", paramName);
-        builder->fsCodeAppend("\t\tdiff = 1 - diff;\n");
+        builder->fsCodeAppend("\t\tdiff = 1.0 - diff;\n");
         builder->fsCodeAppend("\t\tfloat alpha = clamp(diff, 0.0, 1.0);\n");
     } else {
         builder->fsCodeAppendf("\t\tfloat alpha = 1.0;\n");