fail early if coincidence can't be resolved

src/pathops/SkPathOpsCommon.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 "SkAddIntersections.h"
 #include "SkOpEdgeBuilder.h"
 #include "SkPathOpsCommon.h"
 #include "SkPathWriter.h"
@@ skipping 681 matching lines @@
        SkASSERT(sLink[rIndex] == SK_MaxS32);
        SkASSERT(eLink[rIndex] == SK_MaxS32);
     }
 #endif
 }
 
 bool HandleCoincidence(SkTArray<SkOpContour*, true>* contourList, int total) {
 #if DEBUG_SHOW_WINDING
     SkOpContour::debugShowWindingValues(contourList);
 #endif
-    CoincidenceCheck(contourList, total);
+    if (!CoincidenceCheck(contourList, total)) {
+        return false;
+    }
 #if DEBUG_SHOW_WINDING
     SkOpContour::debugShowWindingValues(contourList);
 #endif
     fixOtherTIndex(contourList);
     checkEnds(contourList);  // check if connecting curve intersected at the same end
     bool hasM = checkMultiples(contourList);  // check if intersections agree on t and point values
     SkTDArray<SkOpSegment::AlignedSpan> aligned;
     if (hasM) {
         alignMultiples(contourList, &aligned);  // align pairs of identical points
         alignCoincidence(contourList, aligned);
     }
     checkDuplicates(contourList);  // check if spans have the same number on the other end
     checkTiny(contourList);  // if pair have the same end points, mark them as parallel
     checkSmall(contourList);  // a pair of curves with a small span may turn into coincident lines
     joinCoincidence(contourList);  // join curves that connect to a coincident pair
     sortSegments(contourList);
     if (!calcAngles(contourList)) {
         return false;
     }
     sortAngles(contourList);
 #if DEBUG_ACTIVE_SPANS || DEBUG_ACTIVE_SPANS_FIRST_ONLY
     DebugShowActiveSpans(*contourList);
 #endif
     return true;
 }