Bug
1857218 - Part 1: Rename Nursery::currentStartChunk_ and currentStartPosition_ r=sfink
These members specify the start of the nursery (usually they are zero, but can
be different in generational zeal mode). They are constant between collections.
Calling them 'current' implies that they change often and this could lead to
confusion with currentChunk, which does change between collections. It's
simpler to remove the 'current'.
Differential Revision: https://phabricator.services.mozilla.com/
D190189