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/GrPathRendererChain.cpp b/src/gpu/GrPathRendererChain.cpp
index 9bfa752..f578851 100644
--- a/src/gpu/GrPathRendererChain.cpp
+++ b/src/gpu/GrPathRendererChain.cpp
@@ -61,7 +61,7 @@
 
     for (int i = 0; i < fChain.count(); ++i) {
         GrPathRenderer::CanDrawPathArgs args;
-        args.fTarget = target;
+        args.fShaderCaps = target->caps()->shaderCaps();
         args.fPipelineBuilder = pipelineBuilder;
         args.fViewMatrix = &viewMatrix;
         args.fPath = &path;
@@ -70,7 +70,7 @@
         if (fChain[i]->canDrawPath(args)) {
             if (GrPathRenderer::kNoSupport_StencilSupport != minStencilSupport) {
                 GrPathRenderer::StencilSupport support =
-                    fChain[i]->getStencilSupport(target, pipelineBuilder, path, stroke);
+                                                       fChain[i]->getStencilSupport(path, stroke);
                 if (support < minStencilSupport) {
                     continue;
                 } else if (stencilSupport) {