This issue was originally filed by ross.dart.la...@gmail.com

0.8.1_r28355
Windows 7x64

I am using spawnFunction from dart:isolate to attempt to offload some expensive work from my ui thread. This expensive work needs to make some js-interop calls, but it blows up on the first such call with:

Uncaught Instance of 'UnknownJavaScriptObject'
ReferenceError: window is not defined
    at ReceivePortSync.receive$1 (...)
    at _ProxiedObjectTable._ProxiedObjectTable$0 (...)
    at Object._ProxiedObjectTable.static._ProxiedObjectTable$ (...)
    at Isolate.prototype.(anonymous function) (...)
    at Object._enterScopeIfNeeded (...)

The offending code looks like:

ReceivePortSync: {"": "Object;_portId@-,_callback@-,_portSubscription@-",
  _callback$1: function(arg0) {
    return this._callback.call$1(arg0);
  },
  _callback$0: function() {
    return this._callback.call$0();
  },
  get$_listenerName: function() {
    var t1, t2;
    t1 = W.ReceivePortSync__isolateId();
    t2 = this._portId;
    return "dart-port-" + H.S(t1) + "-" + H.S(t2);
    "18";
  },
  "+_listenerName": 1,
  receive$1: function(callback) {
    var t1, t2, t3;
    this._callback = callback;
    if (this._portSubscription == null) {
      t1 = window; // THIS IS THE PROBLEM
      t2 = W.ReceivePortSync__isolateId();
...

I spent some time trying to figure out precisely where this is coming from but did not succeed. Can I use dart:js instead of js-interop to avoid this, or is it somewhere deeper?

thanks,