datepicker: invalid value on first load from moment

Bug Report

Demo URL (required)*: https://datepicker-invalid-value-on-first-load-from-string-12075-pskwl4.stackblitz.io

Detailed Reproduction Steps

1. Start date as moment object

List the affected versions of AngularJS, Material, OS, and browsers

• AngularJS: 1.8.2
• AngularJS Material: 1.2.3
• OS: All
• Browsers: All
• Screen Readers:

Add anything else we should know

This was just fixed for string being the default last version. I added the below to that ticket, but I added it too late. I should have just opened a new ticket. Sorry about that.

When DatePickerCtrl.prototype.updateErrorState is called with a moment date if (this.dateUtil.isValidDate(date)) { is false So this.ngModelCtrl.$setValidity('valid', date == null); runs and the ngModel ctrl valid key is set to false.