This allows Node.js to enable detailed source positions for optimized code
early on, without having to pass a flag string.

R=petermarshall@chromium.org

Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75
Reviewed-on: https://chromium-review.googlesource.com/c/1319757
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57380}