When collecting source ranges for conditionals (`a ? b : c`), include
the '?' and ':' tokens in the then- and else ranges, respectively.

Bug: v8:7098
Change-Id: I22315e2040c96c977e0b49e1fafe4228a6558471
Reviewed-on: https://chromium-review.googlesource.com/778321Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49484}