Do div-by-zero check for all gpus in ellipse/rr effects.

src/gpu/effects/GrOvalEffect.cpp

Index: src/gpu/effects/GrOvalEffect.cpp
diff --git a/src/gpu/effects/GrOvalEffect.cpp b/src/gpu/effects/GrOvalEffect.cpp
index e033a896d8c8242c2b4874119adeef59faac52e1..97b977f7542b8a357e8700d2c406fa0cf37751e8 100644
--- a/src/gpu/effects/GrOvalEffect.cpp
+++ b/src/gpu/effects/GrOvalEffect.cpp
@@ -317,9 +317,8 @@ void GLEllipseEffect::emitCode(GrGLShaderBuilder* builder,
     builder->fsCodeAppend("\t\tfloat implicit = dot(Z, d) - 1.0;\n");
     // grad_dot is the squared length of the gradient of the implicit.
     builder->fsCodeAppendf("\t\tfloat grad_dot = 4.0 * dot(Z, Z);\n");
-    if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-        builder->fsCodeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-    }
+    // avoid calling inversesqrt on zero.
+    builder->fsCodeAppend("\t\tgrad_dot = max(grad_dot, 1.0e-4);\n");
     builder->fsCodeAppendf("\t\tfloat approx_dist = implicit * inversesqrt(grad_dot);\n");
 
     switch (ee.getEdgeType()) {