performance.now() in workers exists

hr-time/basic.worker.js

@@ -0,0 +1,18 @@
+importScripts("/resources/testharness.js");
+
+test(function() {
+  assert_true((performance !== undefined), "WorkerGlobalScope.performance exists");
+  assert_equals((typeof performance.now), "function");
+}, "WorkerGlobalScope.performance.now() is a function");
+
+test(function() {
+  assert_true(performance.now() > 0);
+}, "WorkerGlobalScope.performance.now() returns a positive number");
+
+test(function() {
+    var now1 = performance.now();
+    var now2 = performance.now();
+    assert_true((now2-now1) >= 0);
+  }, "WorkerGlobalScope.performance.now() difference is not negative");
+
+done();