allow one zero length dash

gm/dashing.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 "gm.h"
 #include "SkCanvas.h"
 #include "SkPaint.h"
 #include "SkDashPathEffect.h"
 
 static void drawline(SkCanvas* canvas, int on, int off, const SkPaint& paint,
                      SkScalar finalX = SkIntToScalar(600), SkScalar finalY = SkIntToScalar(0),
                      SkScalar phase = SkIntToScalar(0), 
                      SkScalar startX = SkIntToScalar(0), SkScalar startY = SkIntToScalar(0)) {
     SkPaint p(paint);
 
     const SkScalar intervals[] = {
         SkIntToScalar(on),
         SkIntToScalar(off),
     };
 
-    p.setPathEffect(SkDashPathEffect::Create(intervals, 2, phase))->unref();
+    SkAutoTUnref<SkPathEffect> effect(SkDashPathEffect::Create(intervals, 2, phase));
+    p.setPathEffect(effect);
     canvas->drawLine(startX, startY, finalX, finalY, p);
 }
 
 // earlier bug stopped us from drawing very long single-segment dashes, because
 // SkPathMeasure was skipping very small delta-T values (nearlyzero). This is
 // now fixes, so this giant dash should appear.
 static void show_giant_dash(SkCanvas* canvas) {
     SkPaint paint;
 
     drawline(canvas, 1, 1, paint, SkIntToScalar(20 * 1000));
@@ skipping 508 matching lines @@
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 DEF_GM(return new DashingGM;)
 DEF_GM(return new Dashing2GM;)
 DEF_GM(return new Dashing3GM;)
 DEF_GM(return new Dashing4GM;)
 DEF_GM(return new Dashing5GM(true);)
 DEF_GM(return new Dashing5GM(false);)