RFR (S) 8215505: Cleanup jvm.cpp obsolete code after JDK-8210094: Better loading of classloader classes

[coleen.phillimore at oracle.com]

Summary: remove dead code, also remove function that is not needed after 
8210094.

Because classes are not unloaded until their initiating class is 
unloaded, the protection domain of the initiating class can not become 
unreferenced, so the cleanup that was removed is not necessary.

Tested with tier1,2  and 
test/hotspot/jtreg/runtime/Dictionary/ClassForName.java for the case 
testing why this was added for bug 
https://bugs.openjdk.java.net/browse/JDK-8175249.

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8215505.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8215505

Thanks,
Coleen