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

third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-canvas-state/2d.state.saverestore.underflow.worker.js

Index: third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-canvas-state/2d.state.saverestore.underflow.worker.js
diff --git a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-canvas-state/2d.state.saverestore.underflow.worker.js b/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-canvas-state/2d.state.saverestore.underflow.worker.js
deleted file mode 100644
index 150a31cf052ebd84a6af418378f61d2434786654..0000000000000000000000000000000000000000
--- a/third_party/WebKit/LayoutTests/imported/wpt/offscreen-canvas/the-canvas-state/2d.state.saverestore.underflow.worker.js
+++ /dev/null
@@ -1,24 +0,0 @@
-// DO NOT EDIT! This test has been generated by tools/gentest.py.
-// OffscreenCanvas test in a worker:2d.state.saverestore.underflow
-// Description:restore() with an empty stack has no effect
-// Note:
-
-importScripts("/resources/testharness.js");
-importScripts("/common/canvas-tests.js");
-
-var t = async_test("restore() with an empty stack has no effect");
-t.step(function() {
-
-var offscreenCanvas = new OffscreenCanvas(100, 50);
-var ctx = offscreenCanvas.getContext('2d');
-
-for (var i = 0; i < 16; ++i)
-    ctx.restore();
-ctx.lineWidth = 0.5;
-ctx.restore();
-_assertSame(ctx.lineWidth, 0.5, "ctx.lineWidth", "0.5");
-
-t.done();
-
-});
-done();