6843292: "Expect to be beyond new region unless impacting another region" assertion too strong
Summary: In the assertion allow for collision with the guard page.
Reviewed-by: tonyp, ysr, jcoomes
6862534: -XX:NewRatio completely ignored when combined with -XX:+UseConcMarkSweepG
Summary: Use NewRatio if it is explicitly set.
Reviewed-by: ysr, jcoomes