Ensure core video block deprecations cannot be overriden

[talldan]

Related #12358
Noticed while working on WordPress/gutenberg#16348

Currently the technique used to extend the video block's behaviour overwrites the core video block's deprecated property:

jetpack/extensions/blocks/videopress/editor.js

Lines 106 to 112 in 4c63a49

	deprecated: [
	{
	attributes: settings.attributes,
	save: settings.save,
	isEligible: attrs => ! attrs.guid,
	},
	],

At the moment this doesn't cause any issues since the core video block doesn't have a deprecated property. If one were to be added, the overwriting that jetpack does would cause invalid blocks.

Changes proposed in this Pull Request:

• Ensure any deprecations added in the core video block are kept by spreading them into the deprecated array.

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

• Bug fix

Testing instructions:

Testings is a little tricky, but something like this should enable reproduction of the issue:

1. Deactivate Jetpack
2. Add a video block to a new post and save the post
3. Modify the core video block so that it has a deprecation, changing the save function (e.g it doesn't matter what it's changed to, something like <div>video test</div> would work
4. Load the post in the editor and ensure there are no validation errors
5. Activate Jetpack
6. Load the post in the editor again

Expected (this branch)
No validation errors should be visible.

Actual (current master)
Activating Jetpack causes a validation error.

Proposed changelog entry for your changes:

• Ensure any deprecations added in the core video block are not overwritten

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello talldan! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer, review, and approve D30059-code before merging this PR. Thank you!

[jetpackbot]

	Warnings
⚠️	The PR is missing at least one [Status] label. Suggestions: [Status] In Progress, [Status] Needs Review

This is an automated check which relies on PULL_REQUEST_TEMPLATE. We encourage you to follow that template as it helps Jetpack maintainers do their job. If you think 'Testing instructions' or 'Proposed changelog entry' are not needed for your PR - please explain why you think so. Thanks for cooperation 🤖

Generated by 🚫 dangerJS against 2929703

[jeherve]

Is this ready for a review, or still in progress? Do you think you could update the labels accordingly?

Thank you!

[talldan]

Hey @jeherve. It should be ready for review, I've added the label. First PR in the jetpack repo, so just learning the ropes.

I'm an a11n, so I can look into D30059-code diff, but probably won't be able to sort it till next week.

Shouldn't hold up a code review though 😄

[matticbot]

talldan, Your synced wpcom patch D30059-code has been updated.

[jeherve]

LGTM!