Rolling v8/build to 4842479bd8da7b9e5eb027f8c15bee533f9c328f

Rolling v8/buildtools to 099f1da55bfe8caa12266371a7eb983698fb1d87

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

Review-Url: https://codereview.chromium.org/2056613002
Cr-Commit-Position: refs/heads/master@{#36837}