Move another set of extension tests to manifest_version 2

chrome/test/data/extensions/api_test/socket/api/background.html

-<script>
-  chrome.test.runTests([
-    function testCreation() {
-      chrome.experimental.socket.create("udp", {},
-        function callback(socketInfo) {
-          chrome.test.assertEq(42, socketInfo.socketId);
-          chrome.test.succeed();
-        });
-    }
-  ]);
-</script>
+<!--
+ * Copyright (c) 2011 The Chromium Authors. All rights reserved.  Use of this
+ * source code is governed by a BSD-style license that can be found in the
+ * LICENSE file.
+-->
+<script src="background.js"></script>