Add .gitattributes file

[Timer]

Windows contributors have to deal with failing test cases due to line endings when comparing to snapshot tests.

See #3065 for reference.

We should create a .gitattributes file which forces these files (all *.js files?) to be checked out with LF line feeds.

[duvet86]

I can help with this, given that it affects me.
Cheers.

[Timer]

Great, thanks!

[ijajmulani]

Hi, looking to get involved in open source projects. If you want I can help you in this.

[ijajmulani]

Here is my PR for same.

[duvet86]

Unfortunately I can't find a way to normalise files using .gitattributes.
The only solution I've found is setting:
git config --global core.autocrlf false

As per stated here:
https://stackoverflow.com/questions/2517190/how-do-i-force-git-to-use-lf-instead-of-crlf-under-windows/13154031#13154031

Cheers Luca