RFR: 8255378: [Vector API] Remove redundant vector length check after JDK-8254814 and JDK-8255210

[Jie Fu]

On Mon, 26 Oct 2020 16:57:19 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Looks good.

Thanks @iwanowww for your review.
May I get a second review for this change?
Thanks.

-------------

PR: https://git.openjdk.java.net/jdk/pull/854