Also remove event.keyIdentifier in getKeyCharString().
Also remove event.keyIdentifier in getKeyCharString().

This was an oversight from a5262f4e68f62a922c9c05d871c4a874f6737a7b.

mrmr1993/vimium,smblott-github/vimium,decaffeinate-examples/vimium,smblott-github/vimium,gdh1995/vimium,gdh1995/vimium,willsALMANJ/vimium,poacher2k/vimium,poacher2k/vimium,willsALMANJ/vimium,mrmr1993/vimium,poacher2k/vimium,mrmr1993/vimium,gdh1995/vimium,decaffeinate-examples/vimium,smblott-github/vimium,willsALMANJ/vimium,philc/vimium,decaffeinate-examples/vimium,philc/vimium,philc/vimium