Update Web Platform Docs

[marcelgerber]

Updated css.json to include the latest data using this Node script.

Note: This may have changed the order of some property values, as they are not yet sorted by any means.

[peterflynn]

@marcelgerber To make the diff less mega-huge & unreadable in every future update (it actually seems to crash my diff app), I wonder if we should just start sorting the top-level entries now. Alphabetical seems fine -- it can't affect anything user-visible, anyway.

[marcelgerber]

@peterflynn The top-level object was already sorted in the MediaWiki output, and we can't sort objects anyway.
The problem were the property values (an array), where order is user-visible. But as they weren't in any useful order anyway, it sounded reasonable to me to sort them alphabetically.

[marcelgerber]

Also, your diff tool will probably still crash, but as a workaround you can beautify the JSON passed to it.

[redmunds]

@marcelgerber PR #10036 updates this same file. I think it's too hard to determine and resolve conflicts with this file so you should delete one or the other.

[marcelgerber]

I decided to only update css.json in this PR as it's probably the one that lands first.
I've also just updated the file again.

[marcelgerber]

I updated this PR with the latest data.
I also dropped the code that used to normalize all URLs to absolute ones. The WPD API does that step itself now, it seems.

Please don't mind the many commits, they represent intermediate states. I'll squash them away anyways.