Enable AA stencil clip for mixed samples

src/gpu/GrPipelineBuilder.h

Index: src/gpu/GrPipelineBuilder.h
diff --git a/src/gpu/GrPipelineBuilder.h b/src/gpu/GrPipelineBuilder.h
index 2bafd9aeabf2cee84cbdbff5191ac88da23bb273..010685b3e2a85dce11a8082aa741810da0a37319 100644
--- a/src/gpu/GrPipelineBuilder.h
+++ b/src/gpu/GrPipelineBuilder.h
@@ -209,7 +209,8 @@ public:
      * than the color buffer. In is scenario, the higher sample rate is resolved during blending.
      */
     bool hasMixedSamples() const {
-        return this->isHWAntialias() && !fRenderTarget->isUnifiedMultisampled();
+        return fRenderTarget->hasMixedSamples() &&
+               (this->isHWAntialias() || !fStencilSettings.isDisabled());
     }
 
     /// @}