fail early if coincidence can't be resolved

src/pathops/SkAddIntersections.cpp

Index: src/pathops/SkAddIntersections.cpp
diff --git a/src/pathops/SkAddIntersections.cpp b/src/pathops/SkAddIntersections.cpp
index 52e751bd08d0129825b3cf0c097c3343d942a521..27422eda5f012a85e7381f866579a8a9a1d00f0e 100644
--- a/src/pathops/SkAddIntersections.cpp
+++ b/src/pathops/SkAddIntersections.cpp
@@ -434,7 +434,7 @@ void AddSelfIntersectTs(SkOpContour* test) {
 
 // resolve any coincident pairs found while intersecting, and
 // see if coincidence is formed by clipping non-concident segments
-void CoincidenceCheck(SkTArray<SkOpContour*, true>* contourList, int total) {
+bool CoincidenceCheck(SkTArray<SkOpContour*, true>* contourList, int total) {
     int contourCount = (*contourList).count();
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
@@ -446,10 +446,13 @@ void CoincidenceCheck(SkTArray<SkOpContour*, true>* contourList, int total) {
     }
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
-        contour->calcCoincidentWinding();
+        if (!contour->calcCoincidentWinding()) {
+            return false;
+        }
     }
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
         contour->calcPartialCoincidentWinding();
     }
+    return true;
 }