Revert "Switch to new expiration protocol."

client/dart.js

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Bootstrap support for Dart scripts on the page as this script.
 if (navigator.webkitStartDart) {
-  var expirationDate = navigator.webkitStartDart();
-  if (expirationDate) {
-    document.body.innerHTML = 'This build has expired on ' + expirationDate + '.  Please download a new Dartium at http://www.dartlang.org/dartium/index.html';
+  if (!navigator.webkitStartDart()) {
+    document.body.innerHTML = 'This build has expired.  Please download a new Dartium at http://www.dartlang.org/dartium/index.html';
   }
 } else {
   // TODO:
   // - Support in-browser compilation.
   // - Handle inline Dart scripts.
   window.addEventListener("DOMContentLoaded", function (e) {
     // Fall back to compiled JS. Run through all the scripts and
     // replace them if they have a type that indicate that they source
     // in Dart code.
     //
@@ skipping 208 matching lines @@
     var result = null;
     var listener = function (e) {
       result = JSON.parse(e.data);
     };
     window.addEventListener(source, listener, false);
     dispatchEvent(target, [source, serialized]);
     window.removeEventListener(source, listener, false);
     return deserialize(result);
   }
 })();