Update CKEditor library to 4.10.1

Thanks for creating this, @kevineinarsson! 👍

It's not mentioned in https://ckeditor.com/blog/CKEditor-4.10.1-released/, but this also includes a fix for https://github.com/ckeditor/ckeditor-dev/issues/727, which is a bug we also reported in Drupal: #2710431: [upstream] StylesCombo plugin fails when using multiple classes, and they're not listed alphabetically.

In other words: this would fix #2710431: [upstream] StylesCombo plugin fails when using multiple classes, and they're not listed alphabetically! We should do explicit manual testing to verify this.

Patch looks great. My new fellow co-maintainer @TwoD told he wanted to verify he got the same patch by doing a build, so I'm leaving this as Needs review. :)

Yep, I was able to reproduce the build. The only differences were the in-file timestamps and slight PNG compression differences (mine were visually indistinguishable but slightly heavier).

We should probably look over the build instructions in build-config.js in another issue.
Kevin pointed out the online builder did not seem to work with our config.
It also seems we've not actually been using the --leave-js-unminified flag, judging by the diffs so far?

Kevin pointed out the online builder did not seem to work with our config.

That has been broken for years :( Nothing we can do there — that's up to the CKEditor team to fix. They know about this. It's just not a priority. Understandably.

It also seems we've not actually been using the --leave-js-unminified flag, judging by the diffs so far?

Correct. Otherwise we'd be shipping much more JS, and would hence force every single user of a D8 site to download many more bytes!

Committed dc19a1b and pushed to 8.7.x. Thanks!

Woot! First time since @TwoD became a co-maintainer (#2979813: Add TwoD as maintainer for the editor.module component) did he help update CKEditor! So glad to have made the bus factor less bad :D

I think we should consider also committing this to 8.6.x. This is still CKEditor 4.10. Just with bugfixes.

I actually RTBC:ed #2983516: Update CKEditor library to 4.10.0 before this. ;)
But, it's certainly Kevin's largest Core commit, and most likely the first one, even though @lauriii's listed as the commit author. ;D

Right, but that time I don't think you did as much digging. Or if you did, I didn't know or forgot. It's good to have you have explicitly stepped through it all :) <3

Cherry-picked to 8.6.x. Thanks!

🎉