Unify looking for symbols with a specific name in the AST Keep only one traverser for looking up symbol nodes by name instead of having two largely identical ones. BUG=angleproject:2267 TEST=angle_unittests Change-Id: I36e906258180e22b7b1353cab79d90266d99fa0e Reviewed-on: https://chromium-review.googlesource.com/836895 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>