This issue was originally filed by @snitko

I decided to create a new issue since the previous one was closed (https://code.google.com/p/dart/issues/detail?id=16244). Although in the previous issue it was said that it was fixed in the 1.2 release, it is not and I still have the following problem when trying to run compiled code. Here's the relevant part of the Dart source code:

List findSubclasses(name) {
  final ms = currentMirrorSystem();
  List subclasses = [];
  ms.libraries.forEach((k,lib) {
    lib.declarations.forEach((k2, c) {
      if(c is ClassMirror && c.superclass != null) {
        final parentClassName = MirrorSystem.getName(c.superclass.simpleName);
        if (parentClassName == name) {
          subclasses.add(c);
        }
      }
    });
  });
  return subclasses;
}

After compiling to Javascript with dart2js (v 1.2), I'm starting to get the following error:

Uncaught Unsupported operation: Cannot find class for: Closure:350 js_helper.dart:1058
wrapExceptionjs_helper.dart:1058
reflectClassByNamejs_mirrors.dart:550
reflectClassByMangledNamejs_mirrors.dart:520
JsClassMirror.get$superclassjs_mirrors.dart:1474
findSubclasses__closure.call$2find_subclasses.dart:10
_LinkedHashMap.forEach$1.H.computeSignature.funccollection_patch.dart:654
J.forEach$1$axbtc_trader.js:82924
UnmodifiableMapView.forEach$1.H.computeSignature.funcjs_mirrors.dart:2376
J.forEach$1$axbtc_trader.js:82924
findSubclasses_closure.call$2find_subclasses.dart:9
_LinkedHashMap.forEach$1.H.computeSignature.funccollection_patch.dart:654
J.forEach$1$axbtc_trader.js:82924
UnmodifiableMapView.forEach$1.H.computeSignature.funcjs_mirrors.dart:2376
J.forEach$1$axbtc_trader.js:82924
findSubclassesfind_subclasses.dart:8
(anonymous function)template.dart:16
prototype.(anonymous function)btc_trader.js:96298
Template.Template$1template.dart:45
Template.static.Template$js_helper.dart:1667
TemplateStack_collect_closure.call$1template_stack.dart:9
ListMixin.forEach$1.H.computeSignature.funclist.dart:55
J.forEach$1$axbtc_trader.js:82924
TemplateStack.static.TemplateStack_collecttemplate_stack.dart:8
maincomponent_temple.dart:21
_IsolateContext.eval$1isolate_helper.dart:247
startRootIsolateisolate_helper.dart:67
(anonymous function)btc_trader.js:96069
init.currentScriptbtc_trader.js:96049
(anonymous function)

The line that the output complains is this one (it is from the code above):

    if(c is ClassMirror && c.superclass != null) {

I guess something's not working quite well with compiling mirrors functionality here.