Bundled Themes: Twenty Twenty remove unnecessary `$css_dependencies` variable...

Bundled Themes: Twenty Twenty remove unnecessary `$css_dependencies` variable in `twentytwenty_block_editor_styles()`.

Removes the unnecessary `$css_dependencies` variable in `twentytwenty_block_editor_styles()`.

Props ocean90, Dency.
Fixes #49986.
Built from https://develop.svn.wordpress.org/trunk@47618


git-svn-id: https://core.svn.wordpress.org/trunk@47393 1a063a9b-81f0-0310-95a4-ce76da25c4cd