Pre-crop filled rects to avoid scissor

include/gpu/GrClip.h

Index: include/gpu/GrClip.h
diff --git a/include/gpu/GrClip.h b/include/gpu/GrClip.h
index e58528114e873f2caa78f807337cdbb30d46b7e1..f070950e6594293cf862a394a3d11d7ebe998a8b 100644
--- a/include/gpu/GrClip.h
+++ b/include/gpu/GrClip.h
@@ -102,6 +102,12 @@ private:
  */
 class GrClip {
 public:
+    // This is the maximum distance that a draw may extend beyond a clip's scissor and still count
+    // as inside. We use a sloppy compare because the draw may have chosen its bounds in a different
+    // coord system. The rationale for 1e-3 is that in the coverage case (and barring unexpected
+    // rounding), as long as coverage stays below 0.5 * 1/256 we ought to be OK.
+    constexpr static SkScalar kScissorIgnoreFuzz = 1e-3f;
+
     virtual bool quickContains(const SkRect&) const = 0;
     virtual void getConservativeBounds(int width, int height, SkIRect* devResult,
                                        bool* isIntersectionOfRects = nullptr) const = 0;