fix path op conic bugs

src/pathops/SkOpSpan.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkOpSpan_DEFINED
 #define SkOpSpan_DEFINED
 
 #include "SkPathOpsDebug.h"
@@ skipping 354 matching lines @@
     SkOpSpan* fPrev;  // previous intersection point
     int fSpanAdds;  // number of times intersections have been added to span
     bool fAligned;
     bool fChased;  // set after span has been added to chase array
     SkDEBUGCODE(int fCount);  // number of pt/t pairs added
     SkDEBUGCODE(int fID);
 };
 
 class SkOpSpan : public SkOpSpanBase {
 public:
+    bool alreadyAdded() const {
+        if (fAlreadyAdded) {
+            return true;
+        }
+        fAlreadyAdded = true;
+        return false;
+    }
+
     bool clearCoincident() {
         SkASSERT(!final());
         if (fCoincident == this) {
             return false;
         }
         fCoincident = this;
         return true;
     }
 
     int computeWindSum();
@@ skipping 114 matching lines @@
 private:  // no direct access to internals to avoid treating a span base as a span
     SkOpSpan* fCoincident;  // linked list of spans coincident with this one (may point to itself)
     SkOpAngle* fToAngle;  // points to next angle from span start to end
     SkOpSpanBase* fNext;  // next intersection point
     int fWindSum;  // accumulated from contours surrounding this one.
     int fOppSum;  // for binary operators: the opposite winding sum
     int fWindValue;  // 0 == canceled; 1 == normal; >1 == coincident
     int fOppValue;  // normally 0 -- when binary coincident edges combine, opp value goes here
     int fTopTTry; // specifies direction and t value to try next
     bool fDone;  // if set, this span to next higher T has been processed
+    mutable bool fAlreadyAdded;
 };
 
 #endif