Set text colour for file block button

[mikachan]

This sets a text colour for the file block button, which overrides a default :visited text colour set by Core here.

Fixes #288.

[carolinan]

I tested the PR, but only in the default theme.json, not variations. The button text is always black, so when hovering over the button, the text is black over black background.

[carolinan]

I think it needs to be

			"core/file": {
				"elements": {
					"button": {
						":visited": {
							"color": {
								"text": "var(--wp--preset--color--contrast)"
							}
						}
					}
				}
			},

But the schema says it is invalid

[mikachan]

Ah that's strange, all the pseudo-states seem to work in the same way as the default button for me. This is what I see on hover:

I don't think the visited state was included when pseudo-state support was added to theme.json.

[carolinan]

It was: WordPress/gutenberg#42096
But was it not added to core then?

[carolinan]

I can confirm it is not in the schema and needs to be added.

[mikachan]

Ugh I'm sorry, the :visited state seems to be working well for me now. I wasn't seeing any new CSS generated for it at all, but I'm guessing it must've been my environment..

I've tested with both the latest GB trunk and just WP 6.1 RC2 (with GB plugin deactivated), and it's working for me in both. Looks like it's just the schema that needs updating for this!

[mikachan]

I've moved the visited setting to elements.button now, for the base theme and all variations. I thought this was cleaner than adding the file block settings.

[mikachan]

I'm going to bring this in as I believe it's the fix that @carolinan originally intended, and I'd like this included in RC3.