ppb_graphics2d_flush: use CAIRO_OPERATOR_SOURCE to avoid ghosting effect
ppb_graphics2d_flush: use CAIRO_OPERATOR_SOURCE to avoid ghosting effect

reuben/freshplayerplugin,grevutiu-gabriel/freshplayerplugin,reuben/freshplayerplugin,reuben/freshplayerplugin,Papapashu/freshplayerplugin,grevutiu-gabriel/freshplayerplugin,Papapashu/freshplayerplugin,Papapashu/freshplayerplugin