Add feature flag for WebAssembly SIMD

Bug: v8:6020
Change-Id: Ie9b3f45d50a6362cdf64ee573c50241b1295d1d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1588525
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#656088}
8 files changed