Tooltip on button doesn't hide if button is disabled on click

[Hypercubed]

Reopening #1926. If a tooltip is attached to a button that is disabled while the tooltip is displayed the hide trigger cannot fire, therefore the tooltip remains open. See this plunk: http://plnkr.co/edit/gjA46FQ8Ln74zgi8IMR2?p=preview

I propose adding the following to the tooltip directive:

attrs.$observe( 'disabled', function ( val ) {
  if (val && ttScope.isOpen ) {
    hide();
  }
});

[Hypercubed]

Fix in PR #3169