RFR: 8299845: Remove obsolete comments in DirtyCardToOopClosure::get_actual_top

[Albert Mingkun Yang]

On Tue, 10 Jan 2023 07:57:34 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Trivial removing stable comments.

Thanks for the review.

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PR: https://git.openjdk.org/jdk/pull/11918