Datepicker placeholder merges with incorrect input (when datepicker lose focus)

[DimaStoyanov]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

When input doesn't meet date format and datepicker lose focus, clear input value

What is the current behavior?

Input value doesn't clean (but bind variable are not assigned to incorrect value) and then placeholder move towards to input value and merges, make it unredeable

What are the steps to reproduce?

Input incorrect value like "adfsdsa" and click mouse out of datepicker.
When previous value of datepicker was not empty need to do previous step twice

Which versions of Angular, MD2, OS, browsers are affected?

Angular 5