Fix missing uint cases for GLSL and ESSL output.
Fix missing uint cases for GLSL and ESSL output.

These were causing assertions in several WebGL2 conformance tests.

BUG=angleproject:882
BUG=angleproject:1084
BUG=483282

Change-Id: I7651c359a528c95469dcbfb5da2715ae4616b49b
Reviewed-on: https://chromium-review.googlesource.com/286592
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Reviewed-by: Zhenyao Mo <655bdf1d95ff956cd68886dd9e86ee5e987c9dbb@chromium.org>
Tested-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

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