WGSL supports select() with vectors, where the condition is a
scalar. To support this in SPIR-V versions older than 1.4, we need to
splat the condition operand to a vector of the same size as the
objects.
Fixed: tint:933
Change-Id: I571af46e74cd7bb24093524ccfed25a3ed612676
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/56340
Auto-Submit: James Price <jrprice@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
James Price