Rolling v8/build to 6d9becf753310daf17f04ac4f0d8c109c364cdd2

Rolling v8/buildtools to aa47d9773d8f4d6254a587a1240b3dc023d54f06

Rolling v8/tools/gyp to bac4680ec9a5c55ab692490b6732999648ecf1e9

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

Review-Url: https://codereview.chromium.org/2123853004
Cr-Commit-Position: refs/heads/master@{#37568}