Enable asm.js -> WebAssembly by default.

Honor disable flag from the chrome side.

BUG=v8:4203
BUG=chromium:590395
R=jam@chromium.org
TBR=bradnelson@chromium.org

(cherry picked from commit 2b2ec4ad531ae43a75973857fb969d18d81a22c3)

Change-Id: I798cc67255d07bbd8404254ec0b6332e77ec0452
Reviewed-on: https://chromium-review.googlesource.com/619293
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Brad Nelson <bradnelson@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#495336}
Reviewed-on: https://chromium-review.googlesource.com/621398
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/branch-heads/3163@{#677}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
2 files changed