updated support for scroll-margin/padding-* properties on safari TP

[fabb]

these properties are supported in Safari Technology Preview.

note that safari still does not support scroll-margin/padding-block/inline-* props
https://webkit.org/blog/11364/release-notes-for-safari-technology-preview-117/

I tested it with Safari TP using this pen, works as expected with both scroll-padding-top and scroll-margin-top: https://codepen.io/fabb64/pen/YzXYQPW

Related:

• Safari does not support scroll-margin #4945 (comment)
• Added Notes on Safari Scroll Anchoring Bugs #5803

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Note that linting fails because Safari 15 is not yet released and therefore not yet contained in browser/safari.json. I'm not sure how to target the TP version of Safari in version_added, please help.

[dakur]

Note that linting fails because Safari 15 is not yet released and therefore not yet contained in browser/safari.json. I'm not sure how to target the TP version of Safari in version_added, please help.

I would emphasize this paragraph for the one who reviews it.

[ddbeck]

Hi @fabb. Thank you for this PR and your patience while I got to reviewing it.

Unfortunately, I don't have a good answer for you on how to represent this in BCD right now. The short version of the story is that we'll need to wait until Apple has at least issued a beta release before adding this data.

The slightly longer version is that, historically, we've had problems with TP-related data. It's difficult to map a TP version to a general Safari release until Apple actually issues a release. Guessing that a TP feature will appear in the next version number sometimes goes poorly (e.g., guessing incorrectly about whether Apple will issue a point release or a new major version or about which TP marks the cutoff for a full Safari release).

I think the next steps here are to:

1. Open an issue to track this and record the background information (e.g., tests) that you've provided here.
2. Reopen this PR when there's a new general Safari version to confirm the changes against.

I'm sorry that it's a bit of a hassle, but without more involvement from Apple in BCD, this is our best workaround. Let me know if you have any questions. Thank you again!

[fabb]

It’s ok to wait. But how does caniuse.com fill its Safari TP cell data?

[ddbeck]

In addition to using MDN's data, caniuse has its own data too (there may be more to it than that even, I'm not that familiar with how caniuse works under the hood).

[fabb]

Hm, but for scroll-margin caniuse.com lists browser-compat-data as source:

[dakur]

I guess it just takes last stable version from MDN data and renders it for TP as well. 🤷‍♂️

[ddbeck]

OK, I've opened #8887 to track this until we get a way to track work-in-progress for Safari or Safari actually releases with these features. Thank you!