Index: src/wp-admin/includes/template.php
===================================================================
--- src/wp-admin/includes/template.php	(revision 25767)
+++ src/wp-admin/includes/template.php	(working copy)
@@ -1685,6 +1685,8 @@
 }
 
 function _wp_admin_html_begin() {
+	global $is_IE;
+
 	$admin_html_class = ( is_admin_bar_showing() ) ? 'wp-toolbar' : '';
 ?>
 <!DOCTYPE html>
@@ -1695,6 +1697,14 @@
 <html xmlns="http://www.w3.org/1999/xhtml" class="<?php echo $admin_html_class; ?>" <?php do_action('admin_xml_ns'); ?> <?php language_attributes(); ?>>
 <!--<![endif]-->
 <head>
+<?php
+	if ( $is_IE ) {
+		// Lock the IE compatibility mode to the highest supported document mode of the browser.
+		?>
+		<meta http-equiv="X-UA-Compatible" content="IE=edge" />
+		<?php
+	}
+?>
 <meta http-equiv="Content-Type" content="<?php bloginfo('html_type'); ?>; charset=<?php echo get_option('blog_charset'); ?>" />
 <?php
 }
