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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/path-objects/2d.path.arcTo.shape.start.worker.js

-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.path.arcTo.shape.start
-// Description:arcTo() draws a straight line from P0 to P1
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("arcTo() draws a straight line from P0 to P1");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-ctx.fillStyle = '#f00';
-ctx.fillRect(0, 0, 100, 50);
-ctx.strokeStyle = '#0f0';
-ctx.lineWidth = 50;
-ctx.beginPath();
-ctx.moveTo(0, 25);
-ctx.arcTo(200, 25, 200, 50, 10);
-ctx.stroke();
-_assertPixel(offscreenCanvas, 1,1, 0,255,0,255, "1,1", "0,255,0,255");
-_assertPixel(offscreenCanvas, 1,48, 0,255,0,255, "1,48", "0,255,0,255");
-_assertPixel(offscreenCanvas, 50,25, 0,255,0,255, "50,25", "0,255,0,255");
-_assertPixel(offscreenCanvas, 98,1, 0,255,0,255, "98,1", "0,255,0,255");
-_assertPixel(offscreenCanvas, 98,48, 0,255,0,255, "98,48", "0,255,0,255");
-
-t.done();
-
-});
-done();