Rolling v8/tools/mb to 3d628fb28050a1deef98e3be5d5b37b5fd8ed27f

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Review-Url: https://codereview.chromium.org/2079213002
Cr-Commit-Position: refs/heads/master@{#37082}