RFR: JDK-8287606: standardize spelling of subtype and supertype etc in comments

[Jonathan Gibbons]

Please review a trivial fix to remove unnecessary hyphens from compound words in comments,
as suggested in an earlier review.

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Commit messages:
 - JDK-8287606: standardize spelling of subtype and supertype etc in comments

Changes: https://git.openjdk.java.net/jdk/pull/8964/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8964&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287606
  Stats: 33 lines in 10 files changed: 0 ins; 0 del; 33 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8964.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8964/head:pull/8964

PR: https://git.openjdk.java.net/jdk/pull/8964