feat(ngPluralize): add support for bind-once in `count`

The 1st commit contains the change and test for adding support for `bindOnce` in `count`.
The 2nd commit contains some nimor refactoring (mainly to avoid repetitive actions).

Closes #10004
(Makes #5452 obsolete)
True !
But shouldn't we rather be fixing `forEach()` ?
(I.e. replacing `obj.hasOwnProperty(...)` with `hasOwnProperty.call(obj, ...)` at https://github.com/angular/angular.js/blob/master/src/Angular.js#L265)