fix pathops fuzz

src/pathops/SkOpContour.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 SkOpContour_DEFINED
 #define SkOpContour_DEFINED
 
 #include "SkOpSegment.h"
@@ skipping 26 matching lines @@
         appendSegment().addConic(pts, weight, this);
     }
 
     void addCubic(SkPoint pts[4]) {
         appendSegment().addCubic(pts, this);
     }
 
     SkOpSegment* addCurve(SkPath::Verb verb, const SkPoint pts[4]);
 
     SkOpSegment* addLine(SkPoint pts[2]) {
+        SkASSERT(pts[0] != pts[1]);
         return appendSegment().addLine(pts, this);
     }
 
     void addQuad(SkPoint pts[3]) {
         appendSegment().addQuad(pts, this);
     }
 
     SkOpSegment& appendSegment() {
         SkOpSegment* result = fCount++
             ? SkOpTAllocator<SkOpSegment>::Allocate(this->globalState()->allocator()) : &fHead;
@@ skipping 354 matching lines @@
     bool fXor;  // set if original path had even-odd fill
     bool fOppXor;  // set if opposite path had even-odd fill
     SkDEBUGCODE(int fID);
     SkDEBUGCODE(mutable int fDebugIndent);
 };
 
 class SkOpContourHead : public SkOpContour {
 };
 
 #endif