Simplify parameters passed to path renderers

It appears that CanDrawPathArgs::fTarget was only ever used to access the shaderCaps and no instances of onGetStencilSupport ever used the drawTarget and pipelineBuilder parameters.

Review URL: https://codereview.chromium.org/1291803006
diff --git a/src/gpu/GrTessellatingPathRenderer.h b/src/gpu/GrTessellatingPathRenderer.h
index aa7be77..7598ceb 100644
--- a/src/gpu/GrTessellatingPathRenderer.h
+++ b/src/gpu/GrTessellatingPathRenderer.h
@@ -21,10 +21,9 @@
 private:
     bool onCanDrawPath(const CanDrawPathArgs& ) const override;
 
-    StencilSupport onGetStencilSupport(const GrDrawTarget*,
-                                       const GrPipelineBuilder*,
-                                       const SkPath&,
-                                       const GrStrokeInfo&) const override;
+    StencilSupport onGetStencilSupport(const SkPath&, const GrStrokeInfo&) const override {
+        return GrPathRenderer::kNoSupport_StencilSupport;
+    }
 
     bool onDrawPath(const DrawPathArgs&) override;