Menu in alt_main does not react to clicks
Steps to reproduce:
1. Log in to the BE.
2. enter ..../typo3/alt_main.php in the URL bar
3. click on Web > Page (or any other menu item)
the page tree is shown, and no error messages on Firefox' error console
No visible result to clicks, and the following error message on the error console:
Fehler: top.rawurlencodeAndRemoveSiteUrl is not a function
I've tested this in the trunk and the 4.2.x branch; I don't know whether 4.1.x is affected as well.
It looks like alt_main isn't used much anymore (or we would have had this bug report much earlier), especially not by the Core developers (alt_main isn't "dog food" anymore). So I suggest to just removed alt_main and all then-unused files for 4.3. This will also make maintenance easier.
(issue imported from #M12312)