This patch turns on the dynamic conversion logic for integer formats
that we must convert to floating point for ESSL 1.0 compatibility. The
converted formats are 1, 2 and 4 channel unnormalized integer.

BUG=angle:560
Change-Id: I3bcc45f1103290613029bc54fdd6012dddb0a03d
Reviewed-on: https://chromium-review.googlesource.com/186700Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>