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-scheme.js

@@ -75,7 +75,7 @@ var SchemeHighlightRules = function() {
             "merge" : true
         }
     ]
-}
+};
 
 };
 
@@ -140,6 +140,7 @@ var MatchingParensOutdent = require("./matching_parens_outdent").MatchingParensO
 var Mode = function() {
     this.HighlightRules = SchemeHighlightRules;
 	this.$outdent = new MatchingParensOutdent();
+    this.$behaviour = this.$defaultBehaviour;
 };
 oop.inherits(Mode, TextMode);