Customize: Begin HTML markup before Customizer script hooks.

This prevents printing styles and scripts before the `<!DOCTYPE>`.

The `_wp_admin_html_begin()` function should precede Customizer script hooks, in case a plugin prints markup inside a hook such as `admin_enqueue_scripts`.

Follow-up to [19995], [27907].

Props sabernhardt.
Fixes #62629.

git-svn-id: https://develop.svn.wordpress.org/trunk@59480 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/customize.php

@@ -100,6 +100,12 @@
 	$wp_customize->set_autofocus( $autofocus );
 }
 
+// Let's roll.
+header( 'Content-Type: ' . get_option( 'html_type' ) . '; charset=' . get_option( 'blog_charset' ) );
+
+wp_user_settings();
+_wp_admin_html_begin();
+
 $registered             = $wp_scripts->registered;
 $wp_scripts             = new WP_Scripts();
 $wp_scripts->registered = $registered;
@@ -126,12 +132,6 @@
  */
 do_action( 'customize_controls_enqueue_scripts' );
 
-// Let's roll.
-header( 'Content-Type: ' . get_option( 'html_type' ) . '; charset=' . get_option( 'blog_charset' ) );
-
-wp_user_settings();
-_wp_admin_html_begin();
-
 $body_class = 'wp-core-ui wp-customizer js';
 
 if ( wp_is_mobile() ) :