RFR: 8279876: Clean up: isAssignableFrom usages in xpath and jdk internal classes [v2]

[Lance Andersen]

On Wed, 6 Apr 2022 01:23:15 GMT, Joe Wang <joehw at openjdk.org> wrote:

>> Clean up the usages of isAssignableFrom in a few xpath and jdk/internal classes where the checks were really about equality or whether they were the exact class types. It was why they worked nonetheless even though some of them were backwards.
>> 
>> Test: existing tests passed.
>
> Joe Wang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   replace with instanceof

Marked as reviewed by lancea (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/8116