Bug 738919. Add reftest for a canvas dash array with a single element. r=mwoodrow.

--HG--
extra : rebase_source : 06afe9bc1401f53a6e6929a5063fd4af3da699cc

layout/reftests/canvas/dash-1-ref.svg

@@ -11,4 +11,8 @@
   <line x1="50px" y1="100px" x2="250px" y2="100px"
         style="stroke-dasharray: 5px, 10px; stroke-dashoffset: 5px;">
   </line>
+  <line x1="50px" y1="150px" x2="250px" y2="150px"
+        style="stroke-dasharray: 5px; stroke-dashoffset: 5px;">
+  </line>
+
 </svg>

layout/reftests/canvas/dash-1.html

@@ -17,6 +17,14 @@ window.onload = function() {
     ctx.lineTo(250, 100);
     ctx.stroke();
     ctx.beginPath();
+
+    ctx.mozDashOffset = 5;
+    ctx.mozDash = [ 5 ];  // 5 on, 5 off
+    ctx.moveTo(50, 150);
+    ctx.lineTo(250, 150);
+    ctx.stroke();
+    ctx.beginPath();
+
 }
   </script>
 </head>