Remove the direct dependency on node::Environment (which is per-context)
from node::ArrayBufferAllocator (which is per-isolate.)
Contexts that want to toggle the zero fill flag, now do so through a
field that is owned by ArrayBufferAllocator. Better, still not great.
PR-URL: https://github.com/nodejs/node/pull/7082
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>