This is used to override the default values for various values (documented
inline) to determine whether or not to actually make a speculative
connection.
Used to determine the maximum number of unused speculative connections
we will have open for a host at any one time
Used to loosen the restrictions nsHttpConnectionMgr::RestrictConnections
to allow more speculative connections when we’re unsure if a host will
connect via SPDY or not.
Used to determine if we will ignore the existence of any currently idle
connections when we decide whether or not to make a speculative
connection.
by default speculative connections are not made to RFC 1918 addresses