[code-reflection] Integrated: Add line number gutter to op viewer

[Gary Frost]

Added line number back to the op viewer tool.

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Commit messages:
 - Add line number gutter to op viewer

Changes: https://git.openjdk.org/babylon/pull/499/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=499&range=00
  Stats: 169 lines in 4 files changed: 141 ins; 15 del; 13 mod
  Patch: https://git.openjdk.org/babylon/pull/499.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/499/head:pull/499

PR: https://git.openjdk.org/babylon/pull/499