don't close a contour with a line if nothing's there

src/pathops/SkPathWriter.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 "SkOpSpan.h"
 #include "SkPathOpsPoint.h"
 #include "SkPathWriter.h"
 #include "SkTSort.h"
@@ skipping 63 matching lines @@
     }
     SkASSERT(fDefer[0]);
     if (!this->matchedLast(pt)) {
         this->finishContour();
         fFirstPtT = fDefer[0] = pt;
     }
 }
 
 void SkPathWriter::finishContour() {
     if (!this->matchedLast(fDefer[0])) {
+        if (!fDefer[1]) {
+          return;
+        }
         this->lineTo();
     }
     if (fCurrent.isEmpty()) {
         return;
     }
     if (this->isClosed()) {
         this->close();
     } else {
         SkASSERT(fDefer[1]);
         fEndPtTs.push(fFirstPtT);
@@ skipping 256 matching lines @@
         }
     } while (rIndex < linkCount);
 #if DEBUG_ASSEMBLE
     for (rIndex = 0; rIndex < linkCount; ++rIndex) {
        SkASSERT(sLink[rIndex] == SK_MaxS32);
        SkASSERT(eLink[rIndex] == SK_MaxS32);
     }
 #endif
     return;
 }