Remove destination pointer from GrCopySurfaceOp

This appears to be surplus to requirements (and the extra call in visitProxies was causing grief for explicit allocation)

Bug: skia:
Change-Id: Icc0b7f04fed96883408d54986b02d0f3756d56c7
Reviewed-on: https://skia-review.googlesource.com/68862
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ops/GrCopySurfaceOp.cpp b/src/gpu/ops/GrCopySurfaceOp.cpp
index 39991d3..7b1c172 100644
--- a/src/gpu/ops/GrCopySurfaceOp.cpp
+++ b/src/gpu/ops/GrCopySurfaceOp.cpp
@@ -80,8 +80,7 @@
 }
 
 void GrCopySurfaceOp::onExecute(GrOpFlushState* state) {
-    if (!fDst.get()->instantiate(state->resourceProvider()) ||
-        !fSrc.get()->instantiate(state->resourceProvider())) {
+    if (!fSrc.get()->instantiate(state->resourceProvider())) {
         return;
     }