Update itext_key_behavior.mixin.js

Added behaviour for keys pagUP ,pagDOWN , HOME, END, TAB and ESC. ( mimic meta key, that on windows i don't know where it is )
Removed rendering of squares in firefox.

Yes but to make it not appear i should delete all my FORK and create new.
Or pull inside a "master sync" commit.
Useless.
Even in sorich87 commit there are things inside that i pulled some request before. This happens when repo are not in sync.