Clean up ValidateMaxParameters It doesn't need to use a traverser, since all function definitions can be found simply by iterating over the children of the root node. BUG=angleproject:2040 TEST=angle_unittests Change-Id: I18a98eff9710485c0cdce73e7fffe124f7d7afb2 Reviewed-on: https://chromium-review.googlesource.com/508791 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>