The way that the strings were generated was erroneously marking 2D
multisample textures as "2D" instead of "2D_MULTISAMPLE". Fix this
by changing how the types are parsed and generated.

Fixes incomplete texture handling of 2D multisample textures.

BUG=angleproject:1390
BUG=angleproject:2167

Change-Id: I8ffffca119cc7ca654ed1fe81cba37b758f9ef9f
Reviewed-on: https://chromium-review.googlesource.com/713585Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>