Convert some pixel tests in fast/canvas into ref tests.

LayoutTests/fast/canvas/fillrect-gradient-zero-stops.html

Index: LayoutTests/fast/canvas/fillrect-gradient-zero-stops.html
diff --git a/LayoutTests/fast/canvas/fillrect-gradient-zero-stops.html b/LayoutTests/fast/canvas/fillrect-gradient-zero-stops.html
index 10856faffa8a0041b4b4c165e8b0cb4061e8b922..2aa5022adaef9dec9f2cb6d609fa9f008540f04c 100644
--- a/LayoutTests/fast/canvas/fillrect-gradient-zero-stops.html
+++ b/LayoutTests/fast/canvas/fillrect-gradient-zero-stops.html
@@ -3,14 +3,9 @@
 The canvas below should show a gradient with zero stops, which according to the specification is filled with transparant black, ie. not visible. This tests <a href="http://bugs.webkit.org/show_bug.cgi?id=13784">Bug 13784, REGRESSION (r13744-13750): Crash with empty gradient when drawing to canvas</a></p>
 <canvas id="c"></canvas>
 <script>
-if (window.testRunner)
-  testRunner.dumpAsTextWithPixelResults();
-
 window.onload = function () {
   var ctx = document.getElementById('c').getContext('2d');
   ctx.fillStyle = ctx.createLinearGradient(0, 0, 0, 50);
   ctx.fillRect(0, 0, 300, 150);
-  ctx.strokeRect(0, 0, 300, 150);
-}
 </script>
 </body>