Upstream navigator.storage.persist()/persisted() tests to WPT

third_party/WebKit/LayoutTests/http/tests/storage/resources/durability-worker.js

-importScripts("/resources/testharness.js");
-
-test(function() { assert_true("storage" in navigator); },
-    "These worker tests require navigator.storage");
-
-test(function() { assert_false("persist" in navigator.storage); },
-    "navigator.storage.persist should not exist in workers");
-
-promise_test(function() {
-    var promise = navigator.storage.persisted();
-    assert_true(promise instanceof Promise,
-        "navigator.storage.persisted() returned a Promise.");
-    return promise.then(function (result) {
-        // Layout tests get canned results, not the value per spec. So testing
-        // their values here would only be testing our test plumbing. But we can
-        // test that the type of the returned value is correct.
-        assert_equals(typeof result, "boolean", result + " should be a boolean");
-    });
-}, "navigator.storage.persisted returns a promise that resolves.");
-
-done();