Fix EXTERNAL and 2D_ARRAY sampler type info. The type info tables were incorrectly using some information. This bug was uncovered after trying to use the tables more. BUG=angleproject:1390 Change-Id: I5eae01f51269bab05746a14bd3caabb614be210a Reviewed-on: https://chromium-review.googlesource.com/659220 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>