Fix regression in definition list parsing

 * Introduced in 220374b36ac70f100333050cffdfc6de8d51876e.

 * Accounts for tables pushing the frame.

 * Fixes the rt of svwiki/Prince_of_Wales_Conference?oldid=22895440

 * Adds a test that exposes a difference in php/parsoid output. It's
   unclear which is more desirable. For now, we'll document the
   behaviour and consider a follow up patch.

Change-Id: I2e8cf99e92246194f335223cc71555d763be3f1c
Merge "Fix regression in definition list parsing"