8219612: compiler.codecache.stress.Helper.TestCaseImpl can't be defined in different runtime package as its nest host Summary: Test rewritten to use top level classes rather then nested ones Reviewed-by: iignatyev, kvn, thartmann

^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/.*