docparser: Add support for 'protected' methods
docparser: Add support for 'protected' methods

Previously we considered them the same as 'private'.

Change-Id: Ib2ec8aa977af0a3ecb92dac44097fcf3abb41caa

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui