Simplify how admin color schemes are enqueued.

Removes a piece of [27111].

fixes #20729.


git-svn-id: https://develop.svn.wordpress.org/trunk@27203 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/deprecated.php

@@ -3413,3 +3413,10 @@ function rich_edit_exists() {
 	return $wp_rich_edit_exists;
 }
 
+/**
+ * Callback formerly fired on the style_loader_src hook. No longer needed.
+ *
+ * @since 2.6.0
+ * @deprecated 3.9.0
+ */
+function wp_style_loader_src() {}