Editor: add block instance element color support for buttons and headings.

Adds support for buttons and headings to the colors and elements block supports, allowing button and heading element colors to be changed on individual blocks.

Props aaronrobertshaw.
Fixes #59309.



git-svn-id: https://develop.svn.wordpress.org/trunk@56604 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/style-engine/class-wp-style-engine.php

@@ -70,6 +70,9 @@ final class WP_Style_Engine {
 					'default' => 'background-color',
 				),
 				'path'          => array( 'color', 'background' ),
+				'css_vars'      => array(
+					'color' => '--wp--preset--color--$slug',
+				),
 				'classnames'    => array(
 					'has-background'             => true,
 					'has-$slug-background-color' => 'color',
@@ -80,6 +83,9 @@ final class WP_Style_Engine {
 					'default' => 'background',
 				),
 				'path'          => array( 'color', 'gradient' ),
+				'css_vars'      => array(
+					'gradient' => '--wp--preset--gradient--$slug',
+				),
 				'classnames'    => array(
 					'has-background'                => true,
 					'has-$slug-gradient-background' => 'gradient',