RFR: 8315999: Improve Date toString performance [v13]

[温绍锦]

On Tue, 12 Sep 2023 22:53:34 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> The reason for not using off++ is that it can be executed out of order, which may result in better performance.
>
> I don't think that would outweigh the extra branch and the increased code size. I'd opt for simplicity.

I've simplified LocalDate::getChars based on your suggestion

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PR Review Comment: https://git.openjdk.org/jdk/pull/15658#discussion_r1324587746