Update comments for vertical_align
Update comments for vertical_align

jasco/WeasyPrint,andrewleech/WeasyPrint,Kozea/WeasyPrint,prepare/TestWeasyPrint,marclaporte/WeasyPrint,Kozea/WeasyPrint,marclaporte/WeasyPrint,andrewleech/WeasyPrint,jasco/WeasyPrint,prepare/TestWeasyPrint