Update ACE Editor to version 1.2.9

The new ACE editor introduces full support for emojis (and, thereby, UTF-16 characters with high- and low-surrogates). Hence, we can remove our custom fix.

Further, this update will allow emojis to be used in pair programming sessions.

vendor/assets/javascripts/ace/mode-textile.js

@@ -113,6 +113,7 @@ var MatchingBraceOutdent = require("./matching_brace_outdent").MatchingBraceOutd
 var Mode = function() {
     this.HighlightRules = TextileHighlightRules;
     this.$outdent = new MatchingBraceOutdent();
+    this.$behaviour = this.$defaultBehaviour;
 };
 oop.inherits(Mode, TextMode);