fix fuzz test that exceeds numeric limit

src/pathops/SkOpSegment.cpp

Index: src/pathops/SkOpSegment.cpp
diff --git a/src/pathops/SkOpSegment.cpp b/src/pathops/SkOpSegment.cpp
index 24f76aa6de1bcc5d01bf11134490131982c62980..41d62369b644dfe12363173375bba0ab47ae0d9c 100644
--- a/src/pathops/SkOpSegment.cpp
+++ b/src/pathops/SkOpSegment.cpp
@@ -1130,7 +1130,9 @@ SkOpSegment* SkOpSegment::nextChase(SkOpSpanBase** startPtr, int* stepPtr, SkOpS
         SkOpPtT* otherPtT = endSpan->ptT()->next();
         other = otherPtT->segment();
         foundSpan = otherPtT->span();
-        otherEnd = step > 0 ? foundSpan->upCast()->next() : foundSpan->prev();
+        otherEnd = step > 0
+                ? foundSpan->upCastable() ? foundSpan->upCast()->next() : nullptr

[mmoroz, 2016/06/29 14:52:35]

Not sure if it is a good idea to use a nested ternary conditional operators. For
me looks not too readable and line length is exceeded by one symbol.

+                : foundSpan->prev();
     } else {
         int loopCount = angle->loopCount();
         if (loopCount > 2) {
@@ -1150,6 +1152,9 @@ SkOpSegment* SkOpSegment::nextChase(SkOpSpanBase** startPtr, int* stepPtr, SkOpS
         foundSpan = endSpan = next->start();
         otherEnd = next->end();
     }
+    if (!otherEnd) {
+        return nullptr;
+    }
     int foundStep = foundSpan->step(otherEnd);
     if (*stepPtr != foundStep) {
         return set_last(last, endSpan);