Edge names are not always string constants and have to be deleted at
some point. Copy them over to StringStorage to allow the embedder
freeing up their copy.

Bug: chromium:936797
Change-Id: I1c1a617c79c2016b3bd30c3460bb7a47edce1b95
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1565903
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60849}