Clean up TIntermTraverser usage Remove default parameters from TIntermTraverser. Also clean up a few dead function declarations in traversers. TEST=angle_unittests, angle_end2end_tests BUG=angleproject:1037 Change-Id: I8d126c6c2d5b53e8b14e23e3d102f204a59323b3 Reviewed-on: https://chromium-review.googlesource.com/275184 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Zhenyao Mo <zmo@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>