RFR: 8274755: Replace 'while' cycles with iterator with enhanced-for in jdk.jdi

[Andrey Turbanov]

There are few places in code where manual while loop is used with Iterator to iterate over Collection.
Instead of manual while cycles it's preferred to use enhanced-for cycle instead: it's less verbose, makes code easier to read and it's less error-prone.
It doesn't have any performance impact: java compiler generates similar code when compiling enhanced-for cycle.

Similar cleanups:
* https://bugs.openjdk.java.net/browse/JDK-8258006
* https://bugs.openjdk.java.net/browse/JDK-8257912

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Commit messages:
 - [PATCH] Replace 'while' cycles with iterator with enhanced-for in jdk.jdi

Changes: https://git.openjdk.java.net/jdk/pull/5577/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5577&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274755
  Stats: 82 lines in 9 files changed: 0 ins; 35 del; 47 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5577.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5577/head:pull/5577

PR: https://git.openjdk.java.net/jdk/pull/5577