stream: fix Readable.wrap objectMode falsy values

A streams1 stream will have its falsy values such as 0, false, or ""
eaten by the upgrade to streams2, even when objectMode is enabled.

Include test for said cases.

Reviewed-by: isaacs <i@izs.me>
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Merge remote-tracking branch 'upstream/v0.10' into v0.10