Convert Service Worker layout tests to W3C testharness-style tests

LayoutTests/http/tests/serviceworker/indexeddb-worker.js

-var port;
-self.addEventListener('message', function(e) {
-    var message = e.data;
-    if ('port' in message) {
-        port = message.port;
-        doIndexedDBTest();
-    }
-});
-function send(action, text) {
-    if (port) port.postMessage({action: action, text: text});
-}
-
-function evalAndLog(s) {
-    send('log', s);
-    try {
-        return eval(s);
-    } catch (ex) {
-        send('fail', 'EXCEPTION: ' + ex);
-        throw ex;
-    }
-}
-
-function debug(s) {
-    send('log', s);
-}
-
-function doIndexedDBTest() {
-    debug('Preparing the database in the service worker');
-    var request = evalAndLog("indexedDB.deleteDatabase('db')");
-    request.onsuccess = function() {
-        request = evalAndLog("indexedDB.open('db')");
-        request.onupgradeneeded = function() {
-            db = request.result;
-            evalAndLog("db.createObjectStore('store')");
-        };
-        request.onsuccess = function() {
-            db = request.result;
-            evalAndLog("tx = db.transaction('store', 'readwrite')");
-            evalAndLog("store = tx.objectStore('store')");
-            evalAndLog("store.put('value', 'key')");
-            tx.oncomplete = function() {
-                send('quit');
-            };
-        };
-    };
-}