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.


Built from https://develop.svn.wordpress.org/trunk@32974


git-svn-id: http://core.svn.wordpress.org/trunk@32945 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/theme-install.php

@@ -102,7 +102,7 @@ include(ABSPATH . 'wp-admin/admin-header.php');
 
 ?>
 <div class="wrap">
-	<h2><?php
+	<h1><?php
 	echo esc_html( $title );
 
 	/**
@@ -120,7 +120,7 @@ include(ABSPATH . 'wp-admin/admin-header.php');
 		echo ' <a href="#" class="upload add-new-h2">' . __( 'Upload Theme' ) . '</a>';
 		echo ' <a href="#" class="browse-themes add-new-h2">' . _x( 'Browse', 'themes' ) . '</a>';
 	}
-	?></h2>
+	?></h1>
 
 	<div class="upload-theme">
 	<?php install_themes_upload(); ?>