RFR: 8272778: Consolidate is_instance and is_instance_inlined in java_lang_String

[Claes Redestad]

On Fri, 20 Aug 2021 13:31:02 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple change of merging `is_instance` and `is_instance_inlined`.
> 
> Test: build

FWIW this looks good to me too. ����

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Marked as reviewed by redestad (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5201