Updated mediawiki/extensions
Project: mediawiki/extensions/Parsoid  cef666f76f9c882ecb13423f3421f1854a46e915

Replace harmony-collections with es6-shim

This solves a major performance regression with es6 Set.

Bug: 53241
Change-Id: I3b2e748d7e37e50fd99bc34f83900374063025ec