Check results from calls to SkCubicClipper::ChopMonoAtY. BUG=613918 GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2006143009 Review-Url: https://codereview.chromium.org/2006143009

diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index aabcafd..5cd6316 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp

@@ -2812,7 +2812,9 @@
 
     // compute the actual x(t) value
     SkScalar t;
-    SkAssertResult(SkCubicClipper::ChopMonoAtY(pts, y, &t));
+    if (!SkCubicClipper::ChopMonoAtY(pts, y, &t)) {
+      return 0;
+    }
     SkScalar xt = eval_cubic_pts(pts[0].fX, pts[1].fX, pts[2].fX, pts[3].fX, t);
     if (SkScalarNearlyEqual(xt, x)) {
         if (x != pts[3].fX || y != pts[3].fY) {  // don't test end points; they're start points
@@ -3049,7 +3051,9 @@
     for (int i = 0; i <= n; ++i) {
         SkPoint* c = &dst[i * 3];
         SkScalar t;
-        SkAssertResult(SkCubicClipper::ChopMonoAtY(c, y, &t));
+        if (!SkCubicClipper::ChopMonoAtY(c, y, &t)) {
+          continue;
+        }
         SkScalar xt = eval_cubic_pts(c[0].fX, c[1].fX, c[2].fX, c[3].fX, t);
         if (!SkScalarNearlyEqual(x, xt)) {
             continue;