Add choke point for modifying non-AA rect draws (e.g., applying clipping)

src/gpu/batches/GrMSAAPathRenderer.cpp

Index: src/gpu/batches/GrMSAAPathRenderer.cpp
diff --git a/src/gpu/batches/GrMSAAPathRenderer.cpp b/src/gpu/batches/GrMSAAPathRenderer.cpp
index 5b49e6b1383d4d630c765015dcf509e080f3fd5a..d38d88600a4874dbe704a9f7f2a02f60778eb0fd 100644
--- a/src/gpu/batches/GrMSAAPathRenderer.cpp
+++ b/src/gpu/batches/GrMSAAPathRenderer.cpp
@@ -658,6 +658,7 @@ bool GrMSAAPathRenderer::internalDrawPath(GrDrawContext* drawContext,
                     GrRectBatchFactory::CreateNonAAFill(paint.getColor(), viewM, bounds, nullptr,
                                                         &localMatrix));
 
+            SkASSERT(GrPipelineBuilder::kBoth_DrawFace == drawFace[p]);
             GrPipelineBuilder pipelineBuilder(paint, drawContext->mustUseHWAA(paint));
             pipelineBuilder.setDrawFace(drawFace[p]);
             if (passes[p]) {