Add offscreen-canvas to the list of wpt directories to skip.

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/pixel-manipulation/2d.imageData.put.unchanged.worker.js

-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.imageData.put.unchanged
-// Description:putImageData(getImageData(...), ...) has no effect
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("putImageData(getImageData(...), ...) has no effect");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-var i = 0;
-for (var y = 0; y < 16; ++y) {
-    for (var x = 0; x < 16; ++x, ++i) {
-        ctx.fillStyle = 'rgba(' + i + ',' + (Math.floor(i*1.5) % 256) + ',' + (Math.floor(i*23.3) % 256) + ',' + (i/256) + ')';
-        ctx.fillRect(x, y, 1, 1);
-    }
-}
-var imgdata1 = ctx.getImageData(0.1, 0.2, 15.8, 15.9);
-var olddata = [];
-for (var i = 0; i < imgdata1.data.length; ++i)
-    olddata[i] = imgdata1.data[i];
-ctx.putImageData(imgdata1, 0.1, 0.2);
-var imgdata2 = ctx.getImageData(0.1, 0.2, 15.8, 15.9);
-for (var i = 0; i < imgdata2.data.length; ++i) {
-    _assertSame(olddata[i], imgdata2.data[i], "olddata[\""+(i)+"\"]", "imgdata2.data[\""+(i)+"\"]");
-}
-
-t.done();
-
-});
-done();