Fixed unexpected blur call

[marlonpp]

I'm using react-dates inside a Drop. This drop is triggered by an input. As of now, when I transition months the drop is getting closed unexpectedly. My drop closes on input blur, and react-dates calls activeElement.blur() after the month transition. I'm not entirely sure why this is there, but I believe it should only be done if the activeElement is a child of your container.

Hopefully this PR looks good to you, otherwise let me know what needs to be changed.

FYI. I added .vscode to .gitignore so that editor files are not accidentally added.

[coveralls]

Coverage remained the same at 86.457% when pulling 8de8df0 on marlonpp:fix-unexpected-blur into d18da3b on airbnb:master.

[ljharb]

This change seems fine, but it does add a new dependency on “contains”; is there a way that this could use a modified https://github.com/airbnb/browser-shims/blob/master/document-contains.js that doesn’t modify the environment?

[ljharb]

Please revert this and add it it your personal global gitignore; individual editors’ files shouldn’t force a change in every repo that individual uses.

[marlonpp]

Hey Jordan,
Thanks for taking a look at it.
I could definitely use it, but don't you think this should be a concern at the application level?
Looking at the code, I see that contains is already being used here.
Also, contains seems to be a very well supported function (https://developer.mozilla.org/en-US/docs/Web/API/Node/contains).

[ljharb]

Fair point :-) in that case, we've already got this issue and your PR doesn't add it, so let's go ahead with it!

I've rebased your branch for you.

[majapw]

LGTM! :)