RFR: 8365643: JShell EditPad out of bounds on Windows

[David Alayachew]

When calling the `setLocationRelativeTo()` method, a null parameter means that it centers the window in the screen. However, any subsequent resizing operations will change only the size, not the location of the window. Understandable, but now the window is no longer centered. So, changing the order of operations.

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Commit messages:
 - Fixing incorrect centering of EditPad window.

Changes: https://git.openjdk.org/jdk/pull/26814/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26814&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365643
  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26814.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26814/head:pull/26814

PR: https://git.openjdk.org/jdk/pull/26814