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/GrQuadPerEdgeAA.h b/src/gpu/ops/GrQuadPerEdgeAA.h
index 2445139..ffcaf8c 100644
--- a/src/gpu/ops/GrQuadPerEdgeAA.h
+++ b/src/gpu/ops/GrQuadPerEdgeAA.h
@@ -17,11 +17,11 @@
 #include "src/gpu/GrVertexWriter.h"
 #include "src/gpu/geometry/GrQuad.h"
 #include "src/gpu/geometry/GrQuadUtils.h"
-#include "src/gpu/ops/GrMeshDrawOp.h"
 #include "src/gpu/ops/GrTextureOp.h"
 
 class GrCaps;
 class GrColorSpaceXform;
+class GrMeshDrawTarget;
 class GrShaderCaps;
 struct GrVertexWriter;
 
@@ -178,7 +178,7 @@
 
     // This method will return the correct index buffer for the specified indexBufferOption.
     // It will, correctly, return nullptr if the indexBufferOption is kTriStrips.
-    sk_sp<const GrBuffer> GetIndexBuffer(GrMeshDrawOp::Target*, IndexBufferOption);
+    sk_sp<const GrBuffer> GetIndexBuffer(GrMeshDrawTarget*, IndexBufferOption);
 
     // What is the maximum number of quads allowed for the specified indexBuffer option?
     int QuadLimit(IndexBufferOption);