Remove virtual test suits virtual/threaded/fast/canvas-toBlob

third_party/WebKit/LayoutTests/virtual/threaded/fast/canvas-toBlob/canvas-toBlob-toDataURL-race-imageEncoder-png.html

-<script src = "../../../../resources/js-test.js"></script>
-<script src = "../../../../fast/canvas/script-tests/canvas-toBlob-toDataURL-race.js"></script>
-<script type = 'text/javascript'>
-description("Verifies if synchronous PNG image encoding (toDataURL) conflicts with asynchronous image encoding (toBlob)");
-
-//Fire a bunch of toBlob operations of canvas to keep the async thread busy
-var j = 0; // due to async nature of toBlob we need a separate counter
-for (var i = 0; i < numToBlobCalls; i++) 
-{
-    canvas.toBlob(function(blob) {
-        url = URL.createObjectURL(blob);
-        testImages[j++].src = url;
-    });
-}
-
-//Then file a bunch of toDataURL operation on main thread, so both threads now compete for image encoding
-for (var i = numToBlobCalls; i < (numToDataURLCalls + numToBlobCalls); i++) 
-{
-    testImages[i].src = canvas.toDataURL();
-}
-</script>