fixed issue displaying modal quickly after closing it

[Josh-a-e]

This solves an issue I encountered where if I am

• using the closeTimeoutMS prop,
• causing the modal to close
• opening the modal again before the specified number of milliseconds has passed

This results in the --before-open classes not getting removed, which causes the modal to be present but invisible in my case (due to its opacity being set to zero by the --before-open classes).

I imagine this is a not entirely uncommon: I had presented a modal to confirm an action and then on confirmation (after a http request had completed) presented another modal to notify the user of outcome (success / failure). The issue being the http request took less than the 400ms I had set on closeTimeoutMS.

[mzabriskie]

@Josh-a-e this looks like a good fix. Would you mind resolving the conflicts, and we'll get it merged?

[Josh-a-e]

@mzabriskie I've merged in the latest master - thanks!

[claydiffrient]

@Josh-a-e Could you squash the 6 commits down to 1 (to keep our history a bit cleaner, and make it easier to reason about) and add a spec? Then I'm happy to merge.

[diasbruno]

This issue seems to be fixed on newer versions. If it still happens, please reopen this PR.