Move a bunch of extension API tests to manifest_version 2.

chrome/test/data/extensions/api_test/apitest/background.html

-<script>
-chrome.test.runTests([
-    // TODO(battre, mkwst): add more tests.
-
-    function testAssertEq() {
-      var chromeTestFail = chrome.test.fail;
-      var messages = "";
-      chrome.test.fail = function (message) { messages += "\n" + message; };
-
-      // Check that assertEq(..., null) doesn't crash.
-      chrome.test.assertEq({test: 1}, null);
-
-      // Check that assertEq(null, ...) doesn't crash.
-      chrome.test.assertEq(null, {test: 1});
-
-      chrome.test.fail = chromeTestFail;
-      chrome.test.assertEq(
-        "\nAPI Test Error in testAssertEq" +
-        "\nActual: null" +
-        "\nExpected: {\"test\":1}" +
-        "\nAPI Test Error in testAssertEq" +
-        "\nActual: {\"test\":1}" +
-        "\nExpected: null",
-        messages);
-      chrome.test.notifyPass();
-    }
-]);
-</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>