Put <dt>/<dd>/<li> in the always-suppressing category of doBlockLevels

Put <dt>/<dd>/<li> in the always-suppressing category of doBlockLevels

This is a clarification of what already happens in practice for lists
generated from wikitext syntax, since that parsing happens
simultaneously.

Parsoid, for its part, does list handling prior to paragraph wrapping,
so must make use of these definitions.

Further, this helps reduce paragraph wrapping in interstitial spacing of
lists from HTML syntax, as spec'd in the tests, though the possibility
isn't eliminated entirely.

The TOC generation code is altered to reduce the number of newlines
emitted in between list items, since those are now left intact.

Change-Id: I6888b6e8e6768b0737565b87924fefa5a06ebd18