This patch add f16 support for a major part of numeric built-in, and
implement corresponding unittests for resolver and backends. This patch
also enable f16 constant evaluation for unary minus operator, `atan2`
and `clamp`.
The following numeric built-ins are not supported yet:
* frexp
* modf
The end-to-end tests for f16 built-in are not added yet.
Bug: tint:1473, tint:1502
Change-Id: If807185617b21c510a1a9c371179a60800c4f875
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/96722
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Zhaoming Jiang <zhaoming.jiang@intel.com>