(Bug 53109) Move data-mw away from manual json attr loading

 * This is both faster and consistent with how we're accessing other
   parsoid attributes. It's also a step towards not having this data in
   the html output.

 * Changes to parserTests and the blacklist are for attribute order.

 * Requires upgrading domino to 1.0.18
   https://github.com/fgnass/domino/pull/48

Change-Id: I1edbc260887d480adf04763b15043c374e27cceb