Proper heading for admin screens.

First step towards restoring a good heading structure in wp-admin.
The previous `<h1>` contained the site title and a link to the front page and was removed with the toolbar refactoring in 3.2.

Props joedolson, afercia.
Fixes #31650.



git-svn-id: https://develop.svn.wordpress.org/trunk@32974 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/themes.php

@@ -124,12 +124,12 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 ?>
 
 <div class="wrap">
-	<h2><?php esc_html_e( 'Themes' ); ?>
+	<h1><?php esc_html_e( 'Themes' ); ?>
 		<span class="title-count theme-count"><?php echo count( $themes ); ?></span>
 	<?php if ( ! is_multisite() && current_user_can( 'install_themes' ) ) : ?>
 		<a href="<?php echo admin_url( 'theme-install.php' ); ?>" class="hide-if-no-js add-new-h2"><?php echo esc_html_x( 'Add New', 'Add new theme' ); ?></a>
 	<?php endif; ?>
-	</h2>
+	</h1>
 <?php
 if ( ! validate_current_theme() || isset( $_GET['broken'] ) ) : ?>
 <div id="message1" class="updated notice is-dismissible"><p><?php _e('The active theme is broken. Reverting to the default theme.'); ?></p></div>