sort out attribution banners of docs assets

Fixes #11976.
This tweaks some of the third-party JS files so that their attribution banners are left intact by UglifyJS. Thus, the minified files contain all necessary copyright notices.
I have also filed applicable upstream pull requests (e.g. https://github.com/imsky/holder/pull/74) so that we won't have to maintain these trivial changes ourselves in the future.