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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/2d.canvas.readonly.worker.js

Index: third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/2d.canvas.readonly.worker.js
diff --git a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/2d.canvas.readonly.worker.js b/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/2d.canvas.readonly.worker.js
deleted file mode 100644
index f2d76f476c122a18cf7f8f05464cd8e5732b9f2f..0000000000000000000000000000000000000000
--- a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/2d.canvas.readonly.worker.js
+++ /dev/null
@@ -1,23 +0,0 @@
-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.canvas.readonly
-// Description:canvas is readonly
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("canvas is readonly");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-var d = ctx.canvas;
-_assertDifferent(offscreenCanvas, d, "offscreenCanvas", "d");
-ctx.canvas = c;
-_assertSame(ctx.canvas, d, "ctx.canvas", "d");
-
-t.done();
-
-});
-done();