Also use package-lock.json rather than npm-shrinkwrap.json as we no longer need to support the latter.
MozReview-Commit-ID: 4yaFcElvhF7
--HG--
rename : npm-shrinkwrap.json => package-lock.json
extra : rebase_source : ae6fcadd8b4a5213fb94cd6426909c2efebfb6a1