a11y: Fix omitted first letter when scrolling
a11y: Fix omitted first letter when scrolling

https://bugzilla.gnome.org/show_bug.cgi?id=657960

jessevdk/vte,rvu95/vte,saitoha/vte-sixel,flaxandteal/gasket-vte,rvu95/vte,rvu95/vte,flaxandteal/gasket-vte,thestinger/vte-ng,flaxandteal/gasket-vte,jessevdk/vte,saitoha/vte-sixel,thestinger/vte-ng,flaxandteal/gasket-vte,saitoha/vte-sixel,rvu95/vte,thestinger/vte-ng,jessevdk/vte,jessevdk/vte