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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.invalidcolour.worker.js

Index: third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.invalidcolour.worker.js
diff --git a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.invalidcolour.worker.js b/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.invalidcolour.worker.js
deleted file mode 100644
index 1fa62f3b17edc44961b4835757237e6ed7881f68..0000000000000000000000000000000000000000
--- a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.invalidcolour.worker.js
+++ /dev/null
@@ -1,25 +0,0 @@
-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.gradient.object.invalidcolour
-// Description:
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-var g = ctx.createLinearGradient(0, 0, 100, 0);
-assert_throws("SYNTAX_ERR", function() { g.addColorStop(0, ""); });
-assert_throws("SYNTAX_ERR", function() { g.addColorStop(0, 'null'); });
-assert_throws("SYNTAX_ERR", function() { g.addColorStop(0, 'undefined'); });
-assert_throws("SYNTAX_ERR", function() { g.addColorStop(0, null); });
-assert_throws("SYNTAX_ERR", function() { g.addColorStop(0, undefined); });
-
-t.done();
-
-});
-done();