deal more consistently with unsortable edges

src/pathops/SkOpSpan.cpp

 /*
  * Copyright 2014 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 231 matching lines @@
             }
             compare = nextC;
         }
         spanPtT->insert(remainder);
 tryNextRemainder:
         remainder = next;
     }
     fSpanAdds += span->fSpanAdds;
 }
 
+int SkOpSpan::computeWindSum() {
+    SkOpGlobalState* globals = this->globalState();
+    SkOpContour* contourHead = globals->contourHead();
+    int windTry = 0;
+    while (!this->sortableTop(contourHead) && ++windTry < SkOpGlobalState::kMaxWindingTries) {
+        ;
+    }
+    return this->windSum();
+}
+
 bool SkOpSpan::containsCoincidence(const SkOpSegment* segment) const {
     SkASSERT(this->segment() != segment);
     const SkOpSpan* next = fCoincident;
     do {
         if (next->segment() == segment) {
             return true;
         }
     } while ((next = next->fCoincident) != this);
     return false;
 }
@@ skipping 36 matching lines @@
 
 void SkOpSpan::setWindSum(int windSum) {
     SkASSERT(!final());
     if (fWindSum != SK_MinS32 && fWindSum != windSum) {
         this->globalState()->setWindingFailed();
         return;
     }
     SkASSERT(!DEBUG_LIMIT_WIND_SUM || abs(windSum) <= DEBUG_LIMIT_WIND_SUM);
     fWindSum = windSum;
 }