fix(formController): do not let removed control effect form

[shahata]

This PR fixes some issues with manually removing and adding controls from forms:

1. Validity changes in removed control do not effect form validity
2. Validity of existing control is taken into account when adding control to form

Closes #9035

[gkalpak]

@shahata: I don't expect it to have a significant impact, but wouldn't it be better to "cache" the parentForm outside the forEach loops:

var formCtrl = ctrl.$$getParentForm();
forEach(stateMap, function(combinedState, key) {
  forEach(ctrl[key], function(value, validationErrorKey) {
    formCtrl.$setValidity(validationErrorKey, combinedState, ctrl);
  });
});

[shahata]

yes, thanks

[jeffbcross]

@tbosch can you take a look?

[btford]

affected

[shahata]

@btford fixed + rebased

[IgorMinar]

We decided to that this was an invalid use of the $addFromControl / $removeFormControl APIs. Those apis are public for the situations when people build their own custom form controls. They are not intended for application code to add/remove existing form controls from the form.

@btford I believe we should close this unless you have some pending task related to this PR.

[btford]

@IgorMinar++

Thanks for your work on this though, @shahata. FWIW, 0563a0a landed since it's still a legit improvement.

Closing.

[shahata]

Hmmm, I thought that this change might be particularly useful if we decide to support the form attribute (see #8917)

[tbosch]

Interesting, didn't know this. Let's revisit this PR when we work on #8917....