lib/core/text: uniformize doc units
lib/core/text: uniformize doc units

A lot of different variations around the doc units were used in the same module.

Signed-off-by: Alexandre Terrasa <b30f4169e054ee7b8c243480bcfcef62416f3b08@moz-code.org>

privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit