Add not_needed function

This can be used to mark variables from a scope as unused, which
means you will not get an error about unused variables for these.

Review-Url: https://codereview.chromium.org/2936923002
Cr-Original-Commit-Position: refs/heads/master@{#483290}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 49be032f4d3274a71b61c0a92f9f747a4b3c90dd
6 files changed
tree: 06f9004e3dcbf613db5eaac6082c2e3f631aeefa
  1. tools/