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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/path-objects/2d.path.isPointInPath.empty.worker.js

-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.path.isPointInPath.empty
-// Description:isPointInPath() works when there is no path
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("isPointInPath() works when there is no path");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-_assertSame(ctx.isPointInPath(0, 0), false, "ctx.isPointInPath(0, 0)", "false");
-
-t.done();
-
-});
-done();