Error message not showing watchlog for scope.

[irfantusneem]

The watchLog is currently broken, it used to show you the last values, but now it's always empty:
https://github.com/angular/angular.dart/blob/master/lib/core/scope.dart#L347

I added the following code in scope.dart to track the issue. is it possible add this sort of debugging support on a permanent basis or fix the watch log. It helps pinpoint the problem a lot faster.

            if (!_identical(value, last)) {
              if (_ttlLeft == 1)
                print('value = $value  last = $last');
              dirty = true;
              watch.last = value;

[mhevery]

The watch log code was removed because in Dart closure.toString() does not return anything useful. Not sure when we will have a good fix for that.