WGSL: unwrap single array element from uniform ...instead of unwrapping the entire array when only one element is being accessed. The is step #4 from the implementation plan in https://docs.google.com/document/d/17Qku1QEbLDhvJS-JJ9lPQAbnuZtLxWhG-ha5eCUhtEY/edit?tab=t.0#bookmark=id.dt9vmixnpdvo Bug: angleproject:376553328 Change-Id: I6c559f44b75cd1d3c4a478141c11f65a33d76bdf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6102117 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Matt Denton <mpdenton@google.com> Reviewed-by: Matt Denton <mpdenton@google.com> Reviewed-by: Liza Burakova <liza@chromium.org>