add conics to path ops

src/pathops/SkOpCubicHull.cpp

Index: src/pathops/SkOpCubicHull.cpp
diff --git a/src/pathops/SkOpCubicHull.cpp b/src/pathops/SkOpCubicHull.cpp
index 11eaa1f8a9b5060e2a7bb8870352546b15a3fbdc..b71f2928e036bdaa1a24d3089f48c739f4b2a2e9 100644
--- a/src/pathops/SkOpCubicHull.cpp
+++ b/src/pathops/SkOpCubicHull.cpp
@@ -14,6 +14,18 @@ static bool rotate(const SkDCubic& cubic, int zero, int index, SkDCubic& rotPath
             return false;
         }
         rotPath = cubic;
+        if (dy) {
+            rotPath[index].fY = cubic[zero].fY;
+            int mask = other_two(index, zero);
+            int side1 = index ^ mask;
+            int side2 = zero ^ mask;
+            if (approximately_equal(cubic[side1].fY, cubic[zero].fY)) {
+                rotPath[side1].fY = cubic[zero].fY;
+            }
+            if (approximately_equal(cubic[side2].fY, cubic[zero].fY)) {
+                rotPath[side2].fY = cubic[zero].fY;
+            }
+        }
         return true;
     }
     for (int index = 0; index < 4; ++index) {