Prevent right-clicks from occasionally messing up the editor content

readInput would, in some cases, take effect even though our textarea
was in context-menu-hack mode.

Author: marijnh

lib/codemirror.js

@@ -534,6 +534,7 @@ var CodeMirror = (function() {
     // to the data in the editing variable, and updates the editor
     // content or cursor if something changed.
     function readInput() {
+      if (leaveInputAlone) return;
       var changed = false, text = input.value, sr = selRange(input);
       if (!sr) return false;
       var changed = editing.text != text, rs = reducedSelection;