Add missing values for CSS mask-border-* properties

[Elchi3]

Summary

Add missing sub-features.

Test results and supporting details

Data taken from existing features on the short-hands, or from initial support of the long-hand properties.

Related issues

Missed in #28138. This is the last one needs filling from what I can tell!

The remaining properties that are still TBD require solving the context question, see #30613.

[github-actions]

Tip: Review these changes grouped by change (recommended for most PRs), or grouped by feature (for large PRs).

[caugner]

It looks like Chromium also supports -webkit-mask-box-image/-webkit-mask-box-image-repeat: round/space/stretch!

console.table(["repeat", "round", "space", "stretch"].map((value) => ({
    value,
    longhand: CSS.supports("-webkit-mask-box-image-repeat", value),
    shorthand: CSS.supports("-webkit-mask-box-image", `url("image.png") ${value}`),
  })));

yields

[
    {
        "value": "repeat",
        "longhand": true,
        "shorthand": true
    },
    {
        "value": "round",
        "longhand": true,
        "shorthand": true
    },
    {
        "value": "space",
        "longhand": true,
        "shorthand": true
    },
    {
        "value": "stretch",
        "longhand": true,
        "shorthand": true
    }
]

[caugner]

Sorry, previous should have been "Request changes", not "Approve".

[Elchi3]

Thanks, this was marked as false in the collector because it doesn't take into account the -webkit-mask-box-image alternative name.

[caugner]

Thanks!