RFR: 8287148: Avoid redundant HashMap.containsKey calls in ExtendedKeyCodes.getExtendedKeyCodeForChar

[Andrey Turbanov]

On Sat, 30 Apr 2022 18:58:56 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

> `sun.awt.ExtendedKeyCodes#regularKeyCodesMap` contains only non-null values. It means we can replace containsKey+get with get+null check.
> It's clearer and a bit faster.

Thank you for review!

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PR: https://git.openjdk.java.net/jdk/pull/8489