Originally Ace wanted to support IE7, but it now seems that they don't care that much about IE9 even.
We have wanted to support only the latest version of firefox/ie/chrome/safari/opera for a while and remove support code. We now have no excuse.
Created attachment 571283 [details] [diff] [review]
This clean in try: https://tbpl.mozilla.org/?tree=Try&rev=15373ad4a778