Move send_nosniff_header() into wp-includes so it can be used in wp-ajax.php. props sivel, fixes #12683

git-svn-id: https://develop.svn.wordpress.org/trunk@13806 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/functions.php

@@ -4081,4 +4081,19 @@ function __return_true() {
  */
 function __return_false() {
 	return false;
-}
+}
+
+/**
+ * Send a HTTP header to disable content type sniffing in browsers which support it.
+ *
+ * @link http://blogs.msdn.com/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
+ * @link http://src.chromium.org/viewvc/chrome?view=rev&revision=6985
+ *
+ * @since 3.0.0
+ * @return none
+ */
+function send_nosniff_header() {
+	@header( 'X-Content-Type-Options: nosniff' );
+}
+
+?>