This reverts commit 36b53089.
This reverts PR #14065.

Turns out Glyphicons is more active than we'd thought.

Now, the zip file is created when running `grunt prep-release`.

[ci skip]

[skip validator]

Refs https://www.w3.org/Bugs/Public/show_bug.cgi?id=27120
Refs #15263

[skip sauce]

It sets `github: true` for us.

The validator no longer complains about it unless the value is different from `content=IE=edge`, see https://www.w3.org/Bugs/Public/show_bug.cgi?id=27091

Fixes #14809.
Closes #14825.

Refs #14388.

Not clear from the spec whether this is invalid per se.
But it is the current best known workaround for Firefox's unusual behavior.

Simplifies the build tooling a teeny bit.
This data file shouldn't need to be updated for v3 ever again.
This task will also be unnecessary in v4.

[skip sauce] [skip validator]

Now we are on par with what we have on the gh-pages dist/ folder.

This reverts commit e31c2edf.

This reverts commit 25ca5131.