For now skip WASM SIMD tests that fail when MIPS SIMD extension
is not available. Turn on these tests again when simd scalar lowering
mechanism supports all WASM SIMD operations.

Bug: 
Change-Id: I4589680147c04716ed66680aaa06639f4f2452d0
Reviewed-on: https://chromium-review.googlesource.com/524082Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Reviewed-by: Miran Karić <Miran.Karic@imgtec.com>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#45721}