Don't scissor draws overlapping the render target's edges
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2135673002

Review-Url: https://codereview.chromium.org/2135673002
diff --git a/include/gpu/GrClip.h b/include/gpu/GrClip.h
index ce0f155..26aab70 100644
--- a/include/gpu/GrClip.h
+++ b/include/gpu/GrClip.h
@@ -46,6 +46,12 @@
         fHasStencilClip = false;
     }
 
+    void makeScissored(SkIRect& scissor) {
+        fClipCoverageFP.reset();
+        fScissorState.set(scissor);
+        fHasStencilClip = false;
+    }
+
     void makeScissoredFPBased(sk_sp<GrFragmentProcessor> fp, SkIRect& scissor) {
         fClipCoverageFP = fp;
         fScissorState.set(scissor);