Twenty Nineteen: Remove the incorrect "flexible-header" tag.

[poena]

In style.css, the tag flexible-header is included.

But the requirements for using this tag is that the theme includes
support for a custom header with the flex-height and/or flex-width parameters.

The theme does not have support for a header image.

Ref: ​https://make.wordpress.org/themes/handbook/review/required/theme-tags/

[mukesh27]

Patch.

[laurelfulford]

Thanks for the report, @poena, and for the patch, @mukesh27!

For the patch, the generated RTL styles also includes a list of the tags -- for completeness, could you also please remove it there? Thanks!

[mukesh27]

Updated patch as suggested by @laurelfulford

[poena]

I can confirm that the patch removes the incorrect tag.

https://core.trac.wordpress.org/ticket/46213

[audrasjb]

I added a PR because the tag also need to be removed from the readme file :)
Looks good to me, now.

[audrasjb]

In 54869:

Twenty Nineteen: Remove the incorrect "flexible-header" tag.

This changeset removes the "flexible-header" tag from Twenty Nineteen, since the requirements for using this tag is that the theme includes support for a custom header with the flex-height and/or flex-width parameters, and Twenty Nineteen does not have support for header image.

Props poena, mukesh27, laurelfulford, audrasjb.
Fixes #46213.

Committed in https://core.trac.wordpress.org/changeset/54869