R=titzer@chromium.org,aseemgarg@chromium.org
BUG= https://code.google.com/p/v8/issues/detail?id=4203
TEST=test-asm-validator, asm-wasm.js
LOG=N

Review URL: https://codereview.chromium.org/1609893002

Cr-Commit-Position: refs/heads/master@{#33421}