Fix popmenu button padding in Mozilla
Fix popmenu button padding in Mozilla

This adds 1px top and bottom padding to popupmenu's button to match its
hover offset. Necessary because of a bug in Mozilla involving box-sizing
of buttons.

sirDonovan/Pokemon-Showdown-Client,Zarel/Pokemon-Showdown-Client,QuiteQuiet/Pokemon-Showdown-Client,submindraikou/Pokemon-Showdown-Client,Zarel/Pokemon-Showdown-Client,submindraikou/Pokemon-Showdown-Client,panpawn/Gold-Client,QuiteQuiet/Pokemon-Showdown-Client,QuiteQuiet/Pokemon-Showdown-Client,asgdf/Pokemon-Showdown-Client,asgdf/Pokemon-Showdown-Client,sirDonovan/Pokemon-Showdown-Client,asgdf/Pokemon-Showdown-Client,Zarel/Pokemon-Showdown-Client,submindraikou/Pokemon-Showdown-Client,panpawn/Gold-Client,asgdf/Pokemon-Showdown-Client,Zarel/Pokemon-Showdown-Client,sirDonovan/Pokemon-Showdown-Client,panpawn/Gold-Client,sirDonovan/Pokemon-Showdown-Client,QuiteQuiet/Pokemon-Showdown-Client