RFR: 8275106: Cleanup Iterator usages in java.desktop

[Andrey Turbanov]

Cycles with 'Iterator' are error-prone. It's better to use more high-level code, which easier to read.
We can use enhanced-for or Collection.removeIf

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Commit messages:
 - [PATCH] Cleanup Iterator usages in java.desktop
 - [PATCH] Cleanup Iterator usages in java.desktop

Changes: https://git.openjdk.java.net/jdk/pull/5871/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5871&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275106
  Stats: 115 lines in 18 files changed: 5 ins; 62 del; 48 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5871.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5871/head:pull/5871

PR: https://git.openjdk.java.net/jdk/pull/5871