allow one zero length dash

src/utils/SkDashPath.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 "SkDashPathPriv.h"
 #include "SkPathMeasure.h"
 #include "SkStrokeRec.h"
@@ skipping 287 matching lines @@
             if (index == count) {
                 index = 0;
             }
 
             // fetch our next dlen
             dlen = intervals[index];
         }
 
         // extend if we ended on a segment and we need to join up with the (skipped) initial segment
         if (meas.isClosed() && is_even(initialDashIndex) &&
-            initialDashLength > 0) {
+            initialDashLength >= 0) {
             meas.getSegment(0, initialDashLength, dst, !addedSegment);
             ++segCount;
         }
     } while (meas.nextContour());
 
     if (segCount > 1) {
         dst->setConvexity(SkPath::kConcave_Convexity);
     }
 
     return true;
 }
 
 bool SkDashPath::FilterDashPath(SkPath* dst, const SkPath& src, SkStrokeRec* rec,
                                 const SkRect* cullRect, const SkPathEffect::DashInfo& info) {
     SkScalar initialDashLength = 0;
     int32_t initialDashIndex = 0;
     SkScalar intervalLength = 0;
     CalcDashParameters(info.fPhase, info.fIntervals, info.fCount,
                        &initialDashLength, &initialDashIndex, &intervalLength);
     return FilterDashPath(dst, src, rec, cullRect, info.fIntervals, info.fCount, initialDashLength,
                           initialDashIndex, intervalLength);
 }