fix fuzz test that exceeds numeric limit

src/pathops/SkOpSegment.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 "SkOpCoincidence.h"
 #include "SkOpContour.h"
 #include "SkOpSegment.h"
 #include "SkPathWriter.h"
@@ skipping 1112 matching lines @@
     SkOpSpanBase* foundSpan;
     SkOpSpanBase* otherEnd;
     SkOpSegment* other;
     if (angle == nullptr) {
         if (endSpan->t() != 0 && endSpan->t() != 1) {
             return nullptr;
         }
         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) {
             return set_last(last, endSpan);
         }
         const SkOpAngle* next = angle->next();
         if (nullptr == next) {
             return nullptr;
         }
 #if DEBUG_WINDING
         if (angle->debugSign() != next->debugSign() && !angle->segment()->contour()->isXor()
                 && !next->segment()->contour()->isXor()) {
             SkDebugf("%s mismatched signs\n", __FUNCTION__);
         }
 #endif
         other = next->segment();
         foundSpan = endSpan = next->start();
         otherEnd = next->end();
     }
+    if (!otherEnd) {
+        return nullptr;
+    }
     int foundStep = foundSpan->step(otherEnd);
     if (*stepPtr != foundStep) {
         return set_last(last, endSpan);
     }
     SkASSERT(*startPtr);
     if (!otherEnd) {
         return nullptr;
     }
 //    SkASSERT(otherEnd >= 0);
     SkOpSpan* origMin = step < 0 ? origStart->prev() : origStart->upCast();
@@ skipping 615 matching lines @@
     int absOut = SkTAbs(outerWinding);
     int absIn = SkTAbs(innerWinding);
     bool result = absOut == absIn ? outerWinding < 0 : absOut < absIn;
     return result;
 }
 
 int SkOpSegment::windSum(const SkOpAngle* angle) const {
     const SkOpSpan* minSpan = angle->start()->starter(angle->end());
     return minSpan->windSum();
 }