Rolling v8/build/gyp to 6ea68631cdabab9b7c5257657567a785a261692e

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

Review URL: https://codereview.chromium.org/1886223002

Cr-Commit-Position: refs/heads/master@{#35463}