Switch GrMeshDrawOp::Target to be the stand alone GrMeshDrawTarget class

The Tessellator classes will survive in the NGA and they use
GrMeshDrawOp::Target - but GrMeshDrawOp will not survive.

This is a prelude to making all the remaining GrOp-derived classes OGA-only.

Bug: skia:11837
Change-Id: I62dc92e5f42d672342113f12dcedf3435fab993f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/419198
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
diff --git a/src/gpu/ops/GrAtlasTextOp.cpp b/src/gpu/ops/GrAtlasTextOp.cpp
index bd5adf4..3727a44 100644
--- a/src/gpu/ops/GrAtlasTextOp.cpp
+++ b/src/gpu/ops/GrAtlasTextOp.cpp
@@ -195,7 +195,7 @@
     return analysis;
 }
 
-void GrAtlasTextOp::onPrepareDraws(Target* target) {
+void GrAtlasTextOp::onPrepareDraws(GrMeshDrawTarget* target) {
     auto resourceProvider = target->resourceProvider();
 
     // If we need local coordinates, compute an inverse view matrix. If this is solid color, the
@@ -334,7 +334,7 @@
 }
 
 void GrAtlasTextOp::createDrawForGeneratedGlyphs(
-        GrMeshDrawOp::Target* target, FlushInfo* flushInfo) const {
+        GrMeshDrawTarget* target, FlushInfo* flushInfo) const {
     if (!flushInfo->fGlyphsToFlush) {
         return;
     }