RFR: 8317534: GenShen: Remove unused code [v2]

[William Kemper]

> Remove unused code, fix typos, remove empty statements

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Restore deleted comment on correct method

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Changes:
  - all: https://git.openjdk.org/shenandoah/pull/335/files
  - new: https://git.openjdk.org/shenandoah/pull/335/files/6918e929..ec8ad460

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=335&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=335&range=00-01

  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah/pull/335.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/335/head:pull/335

PR: https://git.openjdk.org/shenandoah/pull/335