chips: ng-focus not being triggered on focus

[PLPeeters]

Actual Behavior:

• What is the issue? *
  When adding an ng-focus to an mdChips element, it isn't being triggered when the input is focused.
• What is the expected behavior?
  mdChips should trigger ng-focus when focused.

CodePen (or steps to reproduce the issue): *

• CodePen Demo which shows your issue: https://codepen.io/anon/pen/VrJOgL
• Details: The alert isn't triggering as one would expect when the input is focused.

AngularJS Versions: *

• AngularJS Version: 1.4.14
• AngularJS Material Version: 1.1.5

[Splaktar]

Updated CodePen repro using matching AngularJS Material CSS/JS versions and AngularJS 1.6.6. Also added an input that shows ng-focus working properly.