Bug 1013929 - Use the languagechange event instead of a mozSettings observer. r=stas
Merge pull request #19835 from zbraniecki/1013929-languagechange

Bug 1013929 - Use the languagechange event instead of a mozSettings observer. r=stas
Bug 1018498 - Hide drawers when transformed off screen. r=kgrandon
Bug 1017893 - Fix broken references in FTU unit tests. r=fcampo