The feature has been in Nightly for a while, but I would still let it ride the trains to give us more opportunity to fix any possible intermittents rising from removing the #ifdef NIGHTLY_BUILD.
Bug 1619655 Comment 36 Edit History
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The feature has been in Nightly for a while, but I would still let it ride the trains to give us more opportunity to fix any possible intermittents rising from removing the #ifdef NIGHTLY_BUILD (including the one you mentioned).