fix animations not working on iOS 12.3 beta

bigbluebutton-html5/imports/startup/client/base.jsx

bigbluebutton-html5/imports/ui/components/app/styles.scss

...l5/imports/ui/components/audio/audio-controls/styles.scss

...html5/imports/ui/components/audio/audio-modal/styles.scss

...-html5/imports/ui/components/audio/audio-test/styles.scss

...ports/ui/components/audio/permissions-overlay/styles.scss

...ton-html5/imports/ui/components/breakout-room/styles.scss

...html5/imports/ui/components/chat/message-form/styles.scss

...rts/ui/components/external-video-player/modal/styles.scss

...on-html5/imports/ui/components/join-handler/component.jsx

...on-html5/imports/ui/components/loading-screen/styles.scss

...ts/ui/components/presentation/default-content/styles.scss

...components/presentation/presentation-uploader/styles.scss

...tton-html5/imports/ui/components/presentation/styles.scss

bigbluebutton-html5/imports/ui/components/toast/styles.scss

...utton-html5/imports/ui/components/user-avatar/styles.scss

...ebutton-html5/imports/ui/components/user-list/styles.scss

...ser-participants/user-list-item/user-dropdown/styles.scss

...t/user-participants/user-list-item/user-icons/styles.scss

...nt/user-participants/user-list-item/user-name/styles.scss