docs: Add autoprefixer.

[XhmikosR]

Fixes #3797.

The browsers I went with are the ones from Bootstrap v4 just so that we get an idea. We can adapt it as needed of course :)

[coveralls]

Coverage increased (+0.03%) to 91.719% when pulling f72957d on XhmikosR:xmr-autoprefixer into f1662ac on mochajs:master.

[Munter]

This PR highlighted what we consider a flaw in the --browsers switch for assetgraph-builder and we are working on getting an improvement through the build pipelines.

When the update hits it should be enough to have a .browserslistrc and have autoprefixer installed.

We should of course run autoprefixer. I simply forgot it didn't come out of the box when I set up the build system. I'll make the adjustments for the upcoming version of assetgraph-builder on this branch and bump the version when it lands

[plroebuck]

So with the addition of "autoprefixer", is this no longer needed?

Not following how AG-B automagically runs "autoprefixer" for us using "/docs/.browserlistrc",
as "autoprefixer" is not an AG-B dependency.

[XhmikosR]

.browserslistrc doesn't work with the tool you are using thus why I had to add it here.

Not gonna comment on the other stuff, sorry.

[XhmikosR]

And please don't edit my PRs from now on or I'll have to block this. You are doing things wrong.

[Munter]

@XhmikosR I was helping you get this past review and merged. You just reverted the work I did to make that happen. As a maintainer of the docs I find this disrespectful of the time I spent here, especially with the "doing things wrong" comment.

I'm closing this PR and doing the work myself instead then

[XhmikosR]

I'm sorry, but you don't know a single thing about this. I refuse to further engage to any discussion with you.

In fact I'm gonna close any PRs I made and move one. Good luck to the project with such maintainers as you.

[Munter]

As a maintainer of both the mocha docs, and a maintainer of the build system we use I respectfully disagree