Add expiration check into dart.js script.

client/dart.js

Index: client/dart.js
diff --git a/client/dart.js b/client/dart.js
index d0899d1fa6ced6f5140c18f9b6f0e965e458f724..ba0bfa9b9b32a9c69fb53408c11eac853d740027 100644
--- a/client/dart.js
+++ b/client/dart.js
@@ -4,7 +4,9 @@
 
 // Bootstrap support for Dart scripts on the page as this script.
 if (navigator.webkitStartDart) {
-  navigator.webkitStartDart();
+  if (navigator.webkitStartDart()) {

[vsm, 2012/05/16 19:14:01]

Minor nit: I'd suggest changing failure from true to false.  I.e., it'd be more
intuitive to have webkitStartDart return false if it fails.

[Anton Muhin, 2012/05/17 14:20:28]

We need to think out landing process as if I change C++ implementation, people
we fresh builds will be told to upgrade, but there will be no warning to people
with outdated builds.

wdyt, should we change it or maybe leave it as is now?

On 2012/05/16 19:14:01, vsm wrote:

+    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.