RFR(XS): 8211451: ~2.5% regression on compression benchmark starting with 12-b11

[Roland Westrelin]

> Small note. Can you use ProjNode limit_check_proj for insert_loop_limit_check() calls instead of 
> init_control.

This then:

http://cr.openjdk.java.net/~roland/8211451/webrev.02/

Roland.