Previously, the angular-touch library provided by AngularJS was used to
allow click interactions with UI components to work on touch devices
without an uncomfortable ~300ms delay. From AngularJS 1.7.x onward, this
feature of angular-touch is no longer present:
https://docs.angularjs.org/guide/migration#ngtouch
This should be OK - modern browsers will now recognize applications
aimed at touch support via the use of the "viewport" meta tag (which we
use), removing our original need for angular-touch. The same goes for
IE10+.
