Improve usage of window rectangles

src/gpu/batches/GrClearBatch.h

Index: src/gpu/batches/GrClearBatch.h
diff --git a/src/gpu/batches/GrClearBatch.h b/src/gpu/batches/GrClearBatch.h
index 27e19fab6ea059d371c851e18513db10e5660b58..16f1ddd7f40db1687af359f74d1329fec1f10cae 100644
--- a/src/gpu/batches/GrClearBatch.h
+++ b/src/gpu/batches/GrClearBatch.h
@@ -71,6 +71,9 @@ private:
         // same color.
         GrClearBatch* cb = t->cast<GrClearBatch>();
         SkASSERT(cb->fRenderTarget == fRenderTarget);
+        if (!fClip.windowRectsState().cheapEqualTo(cb->fClip.windowRectsState())) {
+            return false;
+        }
         if (cb->contains(this)) {
             fClip = cb->fClip;
             this->replaceBounds(*t);