Fix gpu dashing for case where all intervals are 0.

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"
@@ skipping 36 matching lines @@
 class DashingGM : public skiagm::GM {
 public:
     DashingGM() {}
 
 protected:
 
     SkString onShortName() {
         return SkString("dashing");
     }
 
-    SkISize onISize() { return SkISize::Make(640, 300); }
+    SkISize onISize() { return SkISize::Make(640, 340); }
 
     virtual void onDraw(SkCanvas* canvas) {
         static const struct {
             int fOnInterval;
             int fOffInterval;
         } gData[] = {
             { 1, 1 },
             { 4, 1 },
         };
 
@@ skipping 15 matching lines @@
                              gData[data].fOffInterval * scale,
                              paint);
                     canvas->translate(0, SkIntToScalar(20));
                 }
             }
         }
 
         show_giant_dash(canvas);
         canvas->translate(0, SkIntToScalar(20));
         show_zero_len_dash(canvas);
+        canvas->translate(0, SkIntToScalar(20));
+        // Draw 0 on, 0 off dashed line
+        paint.setStrokeWidth(SkIntToScalar(8));
+        drawline(canvas, 0, 0, paint);
     }
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static void make_unit_star(SkPath* path, int n) {
     SkScalar rad = -SK_ScalarPI / 2;
     const SkScalar drad = (n >> 1) * SK_ScalarPI * 2 / n;
 
     path->moveTo(0, -SK_Scalar1);
@@ skipping 370 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);)