contexify: fix infinite recursion in delete cb

Do not ever call `Delete()` on `proxy_global_`, it will invoke
`GlobalPropertyDeleteCallback` and cause crash because of the infinite
recursion.

fix #7529
child_process: add path to spawn ENOENT Error

Add a file property to the ENOENT Error returned from ChildProcess's
spawn function.

Signed-off-by: Timothy J Fontaine <tjfontaine@gmail.com>