Revert "Convert DstTexture to DstProxy"

This reverts commit 87f7f1c3ce519115141b40f1d8faede437c8f357.

Reason for revert: grumble, grumble

Original change's description:
> Convert DstTexture to DstProxy
> 
> The last GrTexture-based TextureSampler::reset call must be removed before the TextureSamplers can become purely GrTextureProxy-backed
> 
> Split out of: https://skia-review.googlesource.com/c/10484/ (Omnibus: Push instantiation of GrTextures later (post TextureSampler))
> 
> Change-Id: Ic1435177d8b5d9bd3fc38b4903c9baae8205cfb0
> Reviewed-on: https://skia-review.googlesource.com/16908
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> 

TBR=egdaniel@google.com,robertphillips@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I9af52bb222bd2d8cc696250a9efb62afb80edba1
Reviewed-on: https://skia-review.googlesource.com/17203
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrRenderTargetContext.h b/src/gpu/GrRenderTargetContext.h
index 2666d5c..a749046 100644
--- a/src/gpu/GrRenderTargetContext.h
+++ b/src/gpu/GrRenderTargetContext.h
@@ -458,10 +458,10 @@
     // Makes a copy of the proxy if it is necessary for the draw and places the texture that should
     // be used by GrXferProcessor to access the destination color in 'result'. If the return
     // value is false then a texture copy could not be made.
-    bool SK_WARN_UNUSED_RESULT setupDstProxy(GrRenderTargetProxy*,
-                                             const GrClip&,
-                                             const SkRect& opBounds,
-                                             GrXferProcessor::DstProxy* result);
+    bool SK_WARN_UNUSED_RESULT setupDstTexture(GrRenderTargetProxy*,
+                                               const GrClip&,
+                                               const SkRect& opBounds,
+                                               GrXferProcessor::DstTexture* result);
 
     GrRenderTargetOpList* getOpList();