RFR: 8274882: Cleanup redundant boxing in java.desktop

[Andrey Turbanov]

I missed a few places in https://bugs.openjdk.java.net/browse/JDK-8273168

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Commit messages:
 - [PATCH] Cleanup redundant boxing in java.desktop

Changes: https://git.openjdk.java.net/jdk/pull/5834/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5834&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274882
  Stats: 18 lines in 9 files changed: 0 ins; 3 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5834.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5834/head:pull/5834

PR: https://git.openjdk.java.net/jdk/pull/5834