prevent repeated warnings in console

  "Automatically scrolling cursor into view after selection change"
  "this will be disabled in the next version"
  "set editor.$blockScrolling = Infinity to disable this message"

cf. ajaxorg/ace#2499

> [...]  I'm calling a documented API, and it's in turn
> telling me to call an undocumented one.

and angular-ui/ui-ace#104

static/web.js

@@ -575,6 +575,7 @@
  themes = document.getElementById("themes");
  editor = ace.edit("editor");
  set_result.editor = editor;
+ editor.$blockScrolling = Infinity;
  session = editor.getSession();
  themelist = ace.require("ace/ext/themelist");