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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/context.arguments.missing.worker.js

Index: third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/context.arguments.missing.worker.js
diff --git a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/context.arguments.missing.worker.js b/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/context.arguments.missing.worker.js
deleted file mode 100644
index 467b78b0a93ac4a9b31f6b86a3ccaeb67b7d240c..0000000000000000000000000000000000000000
--- a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-offscreen-canvas/context.arguments.missing.worker.js
+++ /dev/null
@@ -1,21 +0,0 @@
-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:context.arguments.missing
-// 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 offscreenCanvas2 = new OffscreenCanvas(100, 50);
-assert_throws(new TypeError(), function() { offscreenCanvas2.getContext(); });
-
-t.done();
-
-});
-done();