Index: src/wp-admin/includes/misc.php
===================================================================
--- src/wp-admin/includes/misc.php	(revision 26659)
+++ src/wp-admin/includes/misc.php	(working copy)
@@ -633,6 +633,18 @@
 }
 add_action('admin_head', '_ipad_meta');
 
+function _admin_font_face_test( $body_class ) {
+	if ( wp_is_mobile() && ! _font_face_support() ) {
+		if ( ! empty( $body_class ) )
+			$body_class .= ' ';
+
+		$body_class .= 'no-font-face';
+	}
+
+	return $body_class;
+}
+add_filter( 'admin_body_class', '_admin_font_face_test' );
+
 /**
  * Check lock status for posts displayed on the Posts screen
  *
Index: src/wp-includes/class-wp-admin-bar.php
===================================================================
--- src/wp-includes/class-wp-admin-bar.php	(revision 26659)
+++ src/wp-includes/class-wp-admin-bar.php	(working copy)
@@ -353,6 +353,9 @@
 				$class .= ' ie9';
 		} elseif ( wp_is_mobile() ) {
 			$class .= ' mobile';
+
+			if ( ! _font_face_support() )
+				$class .= ' no-font-face';
 		}
 
 		?>
Index: src/wp-includes/vars.php
===================================================================
--- src/wp-includes/vars.php	(revision 26659)
+++ src/wp-includes/vars.php	(working copy)
@@ -139,3 +139,13 @@
 
 	return $is_mobile;
 }
+
+function _font_face_support() {
+	$pattern = '/Android (1.0|1.1|1.5|1.6|2.0|2.1)|Nokia|Opera Mini|' .
+		'w(eb)?OSBrowser|webOS|UCWEB|Windows Phone OS 7|XBLWP7|ZuneWP7/';
+
+	if ( preg_match( $pattern, $_SERVER['HTTP_USER_AGENT'] ) )
+		return false;
+
+	return true;
+}