Support non-square matrices in precision emulation In case the shader version is greater than ESSL 1.00, the precision emulation needs to output rounding functions for non-square matrix types. Writing emulated compound assignment functions for non-square matrices already had most of the code in place before this change. New compound assignment operators like >>= don't need floating point precision emulation in ESSL 3.00, since all of them only operate on integers. BUG=angleproject:1434 TEST=angle_unittests Change-Id: I4678f511edf4f9f744fe23bb8d7dab4387f07f20 Reviewed-on: https://chromium-review.googlesource.com/358472 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>