Merge pull request #3987 from OZhurbenko/refs-to-callbacks

.../ui/components/actions-bar/actions-dropdown/component.jsx

...ml5/imports/ui/components/chat/message-form/component.jsx

...ml5/imports/ui/components/chat/message-list/component.jsx

...ponents/chat/message-list/message-list-item/component.jsx

...chat/message-list/message-list-item/message/component.jsx

...html5/imports/ui/components/closed-captions/component.jsx

...button-html5/imports/ui/components/dropdown/component.jsx

...ebutton-html5/imports/ui/components/nav-bar/component.jsx

...uebutton-html5/imports/ui/components/switch/component.jsx

...utton-html5/imports/ui/components/user-list/component.jsx

...orts/ui/components/user-list/user-list-item/component.jsx

...mports/ui/components/whiteboard/shapes/poll/component.jsx