Add a dartdoc comment for RealNode.clock (#137)

Add a dartdoc comment for `RealNode.clock` to quiet an analysis
complaint.
1 file changed
tree: e7d5ff0db9d194a0572e351b66f450b20c1b1a06
  1. contrib/
  2. dev/
  3. packages/
  4. .gitignore
  5. .travis.yml
  6. analysis_options.yaml
  7. appveyor.yml