The datepicker's `date-disabled` validation error does not conform to angular validation error standards, and requires awkward syntax to react to on the front-end.

[Asvarduil]

Reproduction Plunker can be found here

Steps to Reproduce:

Open the reproduction plunker given above.

Observe that the testText control has a min-date of 1/2/2000 and max-date attribute of 12/31/2099.

Enter a value outside of the min/max date range (e.g. 1/1/1900 or 1/1/2100)

Observe that both the form-level and control-level validation messages use the syntax, testform.$error['date-disabled'] and testForm.testText.$error['date-disabled']

In the "Form Error Dictionary Blob" section, observe that the JSON blob has date-disabled as the key.

Observed Behavior:

It's necessary to use testform.$error['date-disabled'] or testForm.testText.$error['date-disabled'] to access the error object for a date being outside of the min/max-date range.

Expected Behavior:

I should be able to use the fluent syntax, testForm.$error.dateDisabled or testForm.testText.$error.dateDisabled when interacting with the dateDisabled validation error on the front end.

[cmichal]

What is the reason for setting disabled control to invalid? I would like to see it fixed.

[Duskfall]

Also observed this error. It messes with my form validation.

[aarosil]

This seems like a bug. The control adds date-disabled property under the forms $error object, but the actual control itself shows valid: true!

[willisd2]

@Asvarduil @wesleycho @BobbieBarker This issue should be fixed with PR #3606. There hasn't been any activity on it in over a month though so I'm not sure when they plan on pulling it in.
PRs #3440 and #3438 are related to this.