Object methods should be usable as filters

[jbdeboer]

e.g.

@NgController(
    selector: '[my-controller]',
    publishAs: 'ctrl'
)
class MyController {
   bool isPalindrome(user) {
     return true;
  }
}

<div ng-repeat="user in ['Otto', 'Notto'] | filter:ctrl.isPalindrome">
  {{user}}
</div>

Is valid, but currently barfs on "ctrl.isPalindrome" changing

[mhevery]

Here is a proposed fix: https://github.com/mhevery/angular.dart/tree/issue-800 But it is blocked on http://dartbug.com/13002 Perhaps we can implement it all to verify that it works (it will fail dart2js) and then wait for dart2js fix before we can merge it in.

[mvuksano]

Closed via #934