So I tested the following cases, which all pass:
cwd diralias -> 250 CWD command successful.
cwd /diralias -> 250 CWD command successful.
cwd /diralias/ -> 250 CWD command successful.
cwd /diralias/filename -> 550 filename: No such directory.
cwd /filealias -> 550 filealias: No such diretory.
cwd /filealias/ -> 550 : No such diretory.
retr filealias -> 150 Opening BINARY mode data connection for file transfer.
retr /filealias -> 150 Opening BINARY mode data connection for file transfer.

Hopefully is the end of the fixes for Chrome browser ftp weirdness
(tries to "CWD" to anything/everything to determine if it's a file or not).