Rename parserTests sections.

This is a mechanical search-and-replace:
 !! input -> !! wikitext
 !! result -> !! html

Change-Id: I2eb0169bfd5d853819e7b6c176eaa7db0a7988db
Combine "Italics and bold" parser test cases.

Combine the php and parsoid versions of the italics and bold test cases.

Note that some of the blacklisted failures are legit bugs; see bug 62569.

Change-Id: I0d5a384f0df862619289665bba760d399df90c88
Combine "Definition List" parser test cases.

Combine the php and parsoid versions of the definition list test cases.

All changes to the blacklist are caused by the change in test titles.

Change-Id: Ia7ed7bbe6405093ca1ed7ef3428321745db2c94c