Rolling v8/build to b81f2a05b5aa7f5b6cf843380eb276897b1ef626

Rolling v8/tools/clang to afdc842603935f994788bf2388e1155528448b2a

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

Review-Url: https://codereview.chromium.org/1961653002
Cr-Commit-Position: refs/heads/master@{#36092}