Using the Builtins::Name type doesn't give use any range safety benefits
over simply using int id's, and it complicates use sites by always
forcing a static_cast<Builtins::Name>(id).

Bug: v8:6624
Change-Id: Id5fcf6800c781c637145ab1d00d821f9ad473321
Reviewed-on: https://chromium-review.googlesource.com/650247
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47823}