md-select multiple is not $dirty after changing selected options

[reesemartin]

Actual Behavior:

• What is the issue? * When changing the selected options in a md-select with the multiple attribute, the form is dirtied but the select is not.
• What is the expected behavior? The form AND select should be dirty.

CodePen (or steps to reproduce the issue): *

• CodePen Demo which shows your issue: http://codepen.io/anon/pen/PmoBrE
• Details: Change the selected items in the multiple select and see that the form is dirty but the select remains pristine.

AngularJS Versions: *

• AngularJS Version: 1.5.8 and 1.5.7
• AngularJS Material Version: 1.1.3 and 1.1.0

Additional Information:

• Browser Type: * Chrome
• Browser Version: * 57.0.2987.133
• OS: * Windows 10
• Stack Traces: No errors

[EladBezalel]

@reesemartin would you mind submitting a pr for that?

[alopezsanchez]

Hello @EladBezalel. PR submitted!