AMP: allow the display of the admin bar in AMP views.

[jeherve]

Fixes #15353

Changes proposed in this Pull Request:

• The admin bar can be used in AMP views since AMP 1.3.1, thanks to AMP Dev mode. We consequently do not need to force-deactivate it.
• Since Likes aren't yet compatible with AMP yet (see Port Likes and Comment Likes to work with AMP #9555), let's remove the Likes iFrame from the admin bar.

Is this a new feature or does it add/remove features to an existing part of Jetpack?

• Internal reference: p1586360434019800-slack-jetpack-plugin
• Follow-up to Comment Likes: do not load on AMP views #14840.

Testing instructions:

• On a brand new site running Twenty Twenty, this branch as well as the most recent of the AMP plugin, go to AMP > General and switch to the "Standard" option.
• Go to your site's frontend; you should still see the admin bar. You should also see no valdation errors linked to the Likes or Comment Likes module.

• You should also not see any empty space in the admin bar, where the Likes button previously was.

• Alternatively, you can also try to activate and configure an ad on your site using the advanced-ads plugin, and make sure no warnings are generated in your error when viewing your site's frontend.

Proposed changelog entry for your changes:

• General: avoid conflicts with other plugins interacting with the AMP plugin and the admin bar.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello jeherve! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer, review, and approve D41598-code before merging this PR. Thank you!

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: May 5, 2020.
Scheduled code freeze: April 28, 2020

Generated by 🚫 dangerJS against 45d7b03

[matticbot]

jeherve, Your synced wpcom patch D41598-code has been updated.

[matticbot]

jeherve, Your synced wpcom patch D41598-code has been updated.

[sergeymitr]

Works great now, nicely done!

[kbrown9]

This looks good to me! I followed the provided testing instructions, and the admin bar looks good. No validation errors were generated.

I also activated the advanced-ads plugin and added the example ads to my test site. I’m not sure if that was a sufficient test, but no errors were generated on my test site.

[jeherve]

Cherry-picked to branch-8.4 in 95d4b87

[jeherve]

r205796-wpcom