[8u] RFR 8191227: Unsafe handle resolution in ConstantOopWriteValue::write_on() / print_on() and LIR_Assembler::jobject2reg()

[Aleksey Shipilev]

Original fix:
  https://bugs.openjdk.java.net/browse/JDK-8191227
  https://hg.openjdk.java.net/jdk/jdk/rev/bb957f109a1f

The patch applies after reshuffling and fuzz. We ship parts of this fix in shenandoah/jdk8u:
  https://mail.openjdk.java.net/pipermail/shenandoah-dev/2020-February/011434.html

I would appreciate reviews w.r.t. its bug tail. It seems to be followed up by JDK-8193699, which
introduced numerous failures in itself. I don't think this fix individually causes those troubles.

8u webrev:
  http://cr.openjdk.java.net/~shade/8191227/webrev.8u.01/

Testing: tier1

-- 
Thanks,
-Aleksey