give up if huge paths have unresolvable coincidence

src/pathops/SkOpCoincidence.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkOpCoincidence_DEFINED
 #define SkOpCoincidence_DEFINED
 
 #include "SkOpTAllocator.h"
@@ skipping 74 matching lines @@
     bool extend(SkOpPtT* coinPtTStart, SkOpPtT* coinPtTEnd, SkOpPtT* oppPtTStart,
         SkOpPtT* oppPtTEnd);
     void findOverlaps(SkOpCoincidence* , SkChunkAlloc* allocator) const;
     void fixAligned();
     void fixUp(SkOpPtT* deleted, SkOpPtT* kept);
 
     bool isEmpty() const {
         return !fHead;
     }
 
-    void mark();
+    bool mark();
 
 private:
     bool addIfMissing(const SkCoincidentSpans* outer, SkOpPtT* over1s, SkOpPtT* over1e,
                       SkChunkAlloc* );
     bool addIfMissing(const SkOpPtT* over1s, const SkOpPtT* over1e,
                       const SkOpPtT* over2s, const SkOpPtT* over2e,
                       double tStart, double tEnd,
                       SkOpPtT* coinPtTStart, const SkOpPtT* coinPtTEnd,
                       SkOpPtT* oppPtTStart, const SkOpPtT* oppPtTEnd,
                       SkChunkAlloc* );
@@ skipping 11 matching lines @@
                  double* overS, double* overE) const;
 
     bool testForCoincidence(const SkCoincidentSpans* outer, const SkOpPtT* testS,
                             const SkOpPtT* testE) const;
     SkCoincidentSpans* fHead;
     SkCoincidentSpans* fTop;
     SkDEBUGCODE_(SkOpGlobalState* fDebugState);
 };
 
 #endif