Make TOC hideable

Currently, if an extension doesn't want a TOC, it has to remove it manually.
This change wraps the TOC in markers that make it easy to remove it in ParserOutput
on demand without fragmenting the parser cache with stuff like "use/not use TOC".

Change-Id: I2889bcb9eb999c9049601e92440132118e1a8a41
(cherry picked from commit 21c1c7d025365540f17be4f7ae19184e1ccca4cc)