Rolling v8/build to b2d15686436cdc17f67c3621c314f8d96b5b6fd9

Rolling v8/tools/clang to 996bab489f816e51dde704bd215fb3403919f07e

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

Review-Url: https://codereview.chromium.org/1992113002
Cr-Commit-Position: refs/heads/master@{#36343}