RFR: 8263621: Convert jdk.compiler to use Stream.toList()

[Ian Graves]

Converting use of `Collectors.toList()` to `Stream.toList()` where appropriate. Per [JDK-8260559](https://bugs.openjdk.java.net/browse/JDK-8260559).

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Commit messages:
 - Converting to Stream.toList()

Changes: https://git.openjdk.java.net/jdk/pull/3629/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3629&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263621
  Stats: 13 lines in 9 files changed: 0 ins; 0 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3629.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3629/head:pull/3629

PR: https://git.openjdk.java.net/jdk/pull/3629