Move some of the adding stencil attachment logic of Gpu and into Render Target.

src/gpu/GrTest.cpp

Index: src/gpu/GrTest.cpp
diff --git a/src/gpu/GrTest.cpp b/src/gpu/GrTest.cpp
index 10ce244122986d666e8c26962f851b55e73683f0..800a9e076cd6fe4135eea665433c9705bf5a9c5f 100644
--- a/src/gpu/GrTest.cpp
+++ b/src/gpu/GrTest.cpp
@@ -256,12 +256,10 @@ private:
 
     void onResolveRenderTarget(GrRenderTarget* target) override { return; }
 
-    bool createStencilAttachmentForRenderTarget(GrRenderTarget*, int width, int height) override {
-        return false;
-    }
-
-    bool attachStencilAttachmentToRenderTarget(GrStencilAttachment*, GrRenderTarget*) override {
-        return false;
+    GrStencilAttachment* createStencilAttachmentForRenderTarget(const GrRenderTarget*,
+                                                                int width,
+                                                                int height) override {
+        return nullptr;
     }
 
     void clearStencil(GrRenderTarget* target) override  {}