Use DOM object with ACE (and not the name)

src/app.js

@@ -157,7 +157,7 @@ var run = function () {
 
   // ----------------- editor ----------------------
 
-  var editor = new Editor('input')
+  var editor = new Editor(document.getElementById('input'))
 
   // ----------------- tabbed menu -------------------
   $('#options li').click(function (ev) {

src/app/editor.js

@@ -8,7 +8,7 @@ require('../mode-solidity.js')
 
 function Editor (editorElement) {
   var editor = ace.edit(editorElement)
-  document.getElementById(editorElement).editor = editor // required to access the editor during tests
+  editorElement.editor = editor // required to access the editor during tests
   var event = new EventManager()
   this.event = event
   var sessions = {}