allow conic chop to fail

tests/PathOpsConicIntersectionTest.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "PathOpsTestCommon.h"
 #include "SkGeometry.h"
 #include "SkIntersections.h"
 #include "Test.h"
@@ skipping 147 matching lines @@
 #endif
 
 static void chopBothWays(const SkDConic& dConic, double t, const char* name) {
     SkConic conic;
     for (int index = 0; index < 3; ++index) {
         conic.fPts[index] = dConic.fPts[index].asSkPoint();
     }
     conic.fW = dConic.fWeight;
     SkConic chopped[2];
     SkDConic dChopped[2];
-    conic.chopAt(SkDoubleToScalar(t), chopped);
+    if (!conic.chopAt(SkDoubleToScalar(t), chopped)) {
+        return;
+    }
     dChopped[0] = dConic.subDivide(0, t);
     dChopped[1] = dConic.subDivide(t, 1);
 #if DEBUG_VISUALIZE_CONICS
     dConic.dump();
 #endif
     chopCompare(chopped, dChopped);
 #if DEBUG_VISUALIZE_CONICS
     writePng(conic, chopped, name);
 #endif
 }
@@ skipping 162 matching lines @@
     }
 }
 
 DEF_TEST(PathOpsConicIntersectionOneOff, reporter) {
     oneOff(reporter, 0, 1);
 }
 
 DEF_TEST(PathOpsConicIntersection, reporter) {
     oneOffTests(reporter);
 }