Issue #1215404 by pillarsdotnet, brianV: Fixed Remove assignment to unused...

Issue #1215404 by pillarsdotnet, brianV: Fixed Remove assignment to unused variable $export_data from book_export_html() function.

core/modules/book/book.pages.inc

@@ -86,7 +86,6 @@ function book_export($type, $nid) {
  */
 function book_export_html($nid) {
   if (user_access('access printer-friendly version')) {
-    $export_data = array();
     $node = node_load($nid);
     if (isset($node->book)) {
       $tree = book_menu_subtree_data($node->book);