It's cleaner to mark internal functions by using the TName class,
similarly to TIntermSymbol.

TEST=angle_unittests
BUG=angleproject:1116

Change-Id: I12a03a3dea42b3fc571fa25a1b11d0161f24de72
Reviewed-on: https://chromium-review.googlesource.com/291621Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>