8219807: C2 crash in IfNode::up_one_dom(Node*, bool)
Summary: Guard against regions degraded to copies.
Reviewed-by: kvn
^build/
^dist/
^.idea/
nbproject/private/
^webrev
^.src-rev$
^.jib/
\.DS_Store
\.metadata/
\.recommenders/
test/nashorn/script/external
test/nashorn/lib
NashornProfile.txt
.*/JTreport/.*
.*/JTwork/.*
.*/.git/.*