Worker: Import "imported/wpt/workers" tests (Retry)

third_party/WebKit/LayoutTests/imported/wpt/workers/constructors/Worker/expected-self-properties.worker.js

+importScripts("/resources/testharness.js");
+
+var expected = ['XMLHttpRequest', 'WebSocket', 'EventSource', 'MessageChannel', 'Worker', 'SharedWorker'];
+for (var i = 0; i < expected.length; ++i) {
+  var property = expected[i];
+  test(function() {
+    assert_true(property in self);
+  }, "existence of " + property);
+}
+
+done();