RFR: 8260577: Unused code in AbstractCompiler after Shark compiler removal

[Tobias Hartmann]

After removal of the Shark compiler with [JDK-8171853](https://bugs.openjdk.java.net/browse/JDK-8171853) in JDK 10, some methods in AbstractCompiler are unused.

Thanks,
Tobias

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Commit messages:
 - 8260577: Unused code in AbstractCompiler after Shark compiler removal

Changes: https://git.openjdk.java.net/jdk/pull/2281/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2281&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260577
  Stats: 19 lines in 4 files changed: 0 ins; 16 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2281.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2281/head:pull/2281

PR: https://git.openjdk.java.net/jdk/pull/2281