fix winding for path ops builder

src/pathops/SkOpContour.cpp

 /*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 #include "SkOpContour.h"
 #include "SkOpTAllocator.h"
 #include "SkPathWriter.h"
 #include "SkReduceOrder.h"
@@ skipping 29 matching lines @@
 void SkOpContour::toPath(SkPathWriter* path) const {
     const SkPoint& pt = fHead.pts()[0];
     path->deferredMove(pt);
     const SkOpSegment* segment = &fHead;
     do {
         segment->addCurveTo(segment->head(), segment->tail(), path, true);
     } while ((segment = segment->next()));
     path->close();
 }
 
+void SkOpContour::toReversePath(SkPathWriter* path) const {
+    const SkPoint& pt = fTail->pts()[0];
+    path->deferredMove(pt);
+    const SkOpSegment* segment = fTail;
+    do {
+        segment->addCurveTo(segment->tail(), segment->head(), path, true);
+    } while ((segment = segment->prev()));
+    path->close();
+}
+
 SkOpSegment* SkOpContour::undoneSegment(SkOpSpanBase** startPtr, SkOpSpanBase** endPtr) {
     SkOpSegment* segment = &fHead;
     do {
         if (segment->done()) {
             continue;
         }
         segment->undoneSpan(startPtr, endPtr);
         return segment;
     } while ((segment = segment->next()));
     return NULL;
 }