Rolling v8/third_party/icu to 2b12f8775d66568f2b2e2bd8246efcfdff40d563

Rolling v8/tools/clang to fc5dab2a77e5a2c69f0095faba5f903d520f0bb5

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

Review URL: https://codereview.chromium.org/1653153003

Cr-Commit-Position: refs/heads/master@{#33653}