demos: Address oversized ButtonWidget (icon-only) in IE & Edge
demos: Address oversized ButtonWidget (icon-only) in IE & Edge

Addressing oversized ButtonWidget for icon only buttons, that don't
carry label with `invisibleLabel` option in IE 10, 11 and Edge 15 & 16.
Regression from I117924d9b17d2fa3836dae8.

Bug: T216582
Change-Id: I7dbd23ac56f9f8d5ea5ac2d35e39cae15fbab2d7

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui