ObjectiveC++: Remove duplicate comment contexts

Summary:
The context "Commentar 1" was the same as "SingleLineComment".
The context "Commentar 2" was the same as "MultiLineComment".
This patch cleans this up and removes the Commentar contexts
in favor of the others.

Test Plan: make test

Reviewers: vkrause

Reviewed By: vkrause

Subscribers: Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D9372