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/gl/GrGLProgram.cpp b/src/gpu/gl/GrGLProgram.cpp
index 8277d6e..ec08bf4 100644
--- a/src/gpu/gl/GrGLProgram.cpp
+++ b/src/gpu/gl/GrGLProgram.cpp
@@ -92,12 +92,7 @@
 
     const GrXferProcessor& xp = pipeline.getXferProcessor();
     SkIPoint offset;
-    GrTextureProxy* dstProxy = pipeline.dstTextureProxy(&offset);
-    GrTexture* dstTexture = nullptr;
-    if (dstProxy) {
-        dstTexture = dstProxy->priv().peekTexture();
-    }
-
+    GrTexture* dstTexture = pipeline.dstTexture(&offset);
     fXferProcessor->setData(fProgramDataManager, xp, dstTexture, offset);
     if (dstTexture) {
         fGpu->bindTexture(nextTexSamplerIdx++, GrSamplerParams::ClampNoFilter(), true,