This issue was originally filed by pimmhog...@gmail.com

Go to try.dartlang.org, then insert and execute this code:
class PointlessValueWrapper {
  PointlessValueWrapper(Type pointlessArgument);
}
main() {
  new PointlessValueWrapper(5);
  new PointlessValueWrapper("Hello!");
}

As expected, line 6 raises a warning.

Now, open the link on the top right in a new tab. You'll see the same code, except the type parameters are missing. Because of this, line 2 now produces an error.

I expect a tokeniser somewhere is misbehaving.

Using Firefox/Nightly (which is at version 10, at the moment).