RFR: 8302120: Prefer ArrayList to LinkedList in AggregatePainter

[Andrey Turbanov]

There is only add/iterator calls on this list. No removes from the head or something like this. Not sure why LinkedList was used, but ArrayList should be preferred as more efficient and widely used (more chances for JIT) collection

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Commit messages:
 - [PATCH] Prefer ArrayList to LinkedList in AggregatePainter

Changes: https://git.openjdk.org/jdk/pull/12254/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12254&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302120
  Stats: 5 lines in 1 file changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12254.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12254/head:pull/12254

PR: https://git.openjdk.org/jdk/pull/12254