bug#13484: 24.3.50; ESC <f10> is undefined

[Juri Linkov]

> The way to reproduce:
> emacs -Q
> ESC <f10>
>
> Emacs says that it is undefined, but it should be defined:
> toggle-frame-maximized is an interactive compiled Lisp function in
> `frame.el'.
> It is bound to <M-f10>.

It is intended to mimic the Gnome key <M-f10> that has
no ESC <f10> equivalent.  But maybe we should also bind ESC <f10>
to allow the users to use it as an Emacs alternative
to the system key <M-f10> when it is taken by Gnome
(both should do the same but there are still some bugs that
prevent the correct processing of the system key on non-GTK builds).