Rolling v8/build to 6b34ef332946c38d33d0c08c1915d4b392808ebb

Rolling v8/tools/mb to 340ee1614f0ab8aa8b1846d10b26426789dbca0e

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

Review-Url: https://codereview.chromium.org/2071073003
Cr-Commit-Position: refs/heads/master@{#37045}