use pathops utils to improve precision of cubic chopping in scan converter

src/pathops/SkDCubicLineIntersection.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkIntersections.h"
 #include "SkPathOpsCubic.h"
 #include "SkPathOpsLine.h"
 
@@ skipping 407 matching lines @@
 }
 
 int SkIntersections::intersectRay(const SkDCubic& cubic, const SkDLine& line) {
     LineCubicIntersections c(cubic, line, this);
     fUsed = c.intersectRay(fT[0]);
     for (int index = 0; index < fUsed; ++index) {
         fPt[index] = cubic.ptAtT(fT[0][index]);
     }
     return fUsed;
 }
+
+// SkDCubic accessors to Intersection utilities
+
+int SkDCubic::horizontalIntersect(double yIntercept, double roots[3]) const {
+    return LineCubicIntersections::HorizontalIntersect(*this, yIntercept, roots);
+}
+
+int SkDCubic::verticalIntersect(double xIntercept, double roots[3]) const {
+    return LineCubicIntersections::VerticalIntersect(*this, xIntercept, roots);
+}