RFR: 8357688: Remove unnecessary List.get before remove in PopupFactory

[Andrey Turbanov]

Instead of separate List.get+List.remove calls we can use single `removeFirst`. It's clearer.

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Commit messages:
 - [PATCH] Remove unnecessary List.get before remove in PopupFactory

Changes: https://git.openjdk.org/jdk/pull/25283/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25283&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357688
  Stats: 13 lines in 1 file changed: 0 ins; 6 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/25283.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25283/head:pull/25283

PR: https://git.openjdk.org/jdk/pull/25283