Switch to Node v6.11
Switch to Node v6.11

Bug: T170548
Change-Id: Ifb679f7f530cf9e3bc9c8a38fa99b2511bca58ad

wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps