Updated mediawiki/extensions
Project: mediawiki/extensions/Parsoid  6d4192cd84b8c2d8f8aa7267269c8325cb914de5

Check JSDOM getAttribute behavior an bail out if out of date

An out-of-date JSDOM version (< 0.4.x) will result in random failures as
getAttribute for non-existing keys returns the empty string instead of null.
Test for this and bail out with a helpful message if that is the case.

Change-Id: I9375d6dd74415de3a5ddbe20ea3526ed6d078c00