RFR: 8285364: Remove REF_ enum for java.lang.ref.Reference [v3]

[Albert Mingkun Yang]

On Fri, 22 Apr 2022 09:43:45 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Simple rename and some comments update.
>> 
>> Test: build
>
> Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove REF_ enum for java.lang.ref.Reference
>   
>   Signed-off-by: Albert Yang <albert.m.yang at oracle.com>

I have taken "Rework reference type initialization" from Stefan and added comments on a potential surprise that `j.l.r.Reference` is `instanceKlass` not `instanceRefKlass`.

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PR: https://git.openjdk.java.net/jdk/pull/8332