Port Menu attributes to Drupal 8

Work on a Drupal 8 port of Menu Attributes has happened in a few places:

• A sandbox project by user shanethehat. Hasn't been worked on since May 2013 → .
• A custom module by @bobrov1989 (#14). Does not work with the current D8 (#16) and author isn't currently able to update it (#18).
• A custom module by @agoradesign posted in this blog entry. This only provides the ability to add a class attribute (#16). Does not work with the current D8 and the author is not planning to update it (#19).
• A new module by @yannickoo, Menu Link Attributes → . Currently on beta1 and working with the latest D8 release. Author is interested in merging that module back into Menu Attributes (#25).
• A new link widget by @larowlan - Link attributes widget → - that works for link fields on other entities too

Proposal

While the earlier projects might provide helpful information (and their authors might be interested in helping to port the module) it seems like Menu Link Attributes → is the furthest along in terms of features and being in working order. As @yannickoo is interested in merging the module back into this one, that seems like a viable path.

Next steps:

1. See what can be merged in from the link module, there may be some gems or tests that could be ported
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3. Ensure the menu and menu link form alterations are showing up as configured
4. Ensure the menu link altering is actually feeding the menu output
5. Try to enable and adjust the existing tests and get them to work
6. Check if we need to add any cache contexts

Original issue:

When I looked for a Drupal 8 port, I found this sandbox project using Google. But there is no mention about this (unofficial?) port in the issue queue.

Are there any plans to port menu_attributes to Drupal 8?