BUG: Timeline not scrolling properly with mousewheel on firefox

[jferragut]

Behavior: The issue is that scrolling is slow and janky to the point of frustration for users. Already had a few students complain. The following line appears to be the source.

https://github.com/breatheco-de/student-client/blob/7acde84586e0e1d4262a9ec791fc2fccdaed79db/src/js/components/menus/TimeLineMenu.js#L51

Expectation: In chrome, the scrolling is smooth and at normal speed. Firefox should be the same.

Browser: Firefox only OS: Linux, Mac, Windows 10

Reproduction steps:

• Open Firefox
• Go to Syllabus (timeline)
• Scroll the timeline with mouse wheel
• Scrolling is slow and jagged.

[jferragut]

The current wheel handler and ref were the issue. To resolve, I removed the offending code. Scrolls perfectly in firefox and chrome now.

[jferragut]

Completed with PR #29