Access to TFunction parameters is now handled through two new members:
a pointer to a parameter array and a parameter count.

There's still also a vector pointer in TFunction for adding function
parameters one by one. This is used when parsing user-defined
functions.

TEST=angle_unittests
BUG=angleproject:2267

Change-Id: I86987ae56b7cf37f010d0651e9861789050aec2b
Reviewed-on: https://chromium-review.googlesource.com/923987Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>