RFR: 8360303: Remove two unused invoke files

[Chen Liang]

On Mon, 23 Jun 2025 22:48:52 GMT, Chen Liang <liach at openjdk.org> wrote:

> sun.invoke.empty.Empty and java.lang.invoke.InvokeDynamic are useless remnants - Empty can be replaced by java.lang.Void, and InvokeDynamic was previously used as a stub for javac to compile signature polymorphic methods. They should be removed as a cleanup.
> 
> Testing: tier 1-3

It was added in https://github.com/openjdk/jdk/commit/cd74d63c1299e11aaf6c6ac0c496bd2b091120fa as a compiler stub. If another implementation wishes to keep this class, they can still have a copy as this class is package-private. Otherwise, there is no text occurrence of `invoke.InvokeDynamic` or `invoke/InvokeDynamic` that refers to this class.

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PR Comment: https://git.openjdk.org/jdk/pull/25944#issuecomment-3001537747