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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/path-objects/2d.path.lineTo.nonfinite.details.worker.js

-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.path.lineTo.nonfinite.details
-// Description:lineTo() with Infinity/NaN for first arg still converts the second arg
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("lineTo() with Infinity/NaN for first arg still converts the second arg");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-for (var arg1 of [Infinity, -Infinity, NaN]) {
-  var converted = false;
-  ctx.lineTo(arg1, { valueOf: function() { converted = true; return 0; } });
-  _assert(converted, "converted");
-}
-
-t.done();
-
-});
-done();