General: use a new function, wp_is_IE(), instead of the $is_IE global in a number of places.

See #37699.

Built from https://develop.svn.wordpress.org/trunk@38467


git-svn-id: http://core.svn.wordpress.org/trunk@38408 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/link-template.php

@@ -2896,15 +2896,11 @@ function the_comments_pagination( $args = array() ) {
  * Retrieves the Press This bookmarklet link.
  *
  * @since 2.6.0
- *
- * @global bool          $is_IE      Whether the browser matches an Internet Explorer user agent.
  */
 function get_shortcut_link() {
-	global $is_IE;
-
 	$link = '';
 
-	if ( $is_IE ) {
+	if ( wp_is_IE() ) {
 		/*
 		 * Return the old/shorter bookmarklet code for MSIE 8 and lower,
 		 * since they only support a max length of ~2000 characters for