All the information stored in TFunctionSymbolInfo was duplicated from
the TFunction that the aggregate node pointed to.

BUG=angleproject:2267
TEST=angle_unittests

Change-Id: I1f5574ab0416e5cae00c3dae6fc11d2fe1fa128c
Reviewed-on: https://chromium-review.googlesource.com/827065Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>