This will be synced with an announcement on v8-dev. This
doesn't affect directly calling gyp in our old Makefiles.

BUG=chromium:474921
NOTRY=true

Committed: https://crrev.com/94f813e8dcd4ed5a67cede8af0f949009beaa501
Review-Url: https://codereview.chromium.org/2327033002
Cr-Original-Commit-Position: refs/heads/master@{#39308}
Cr-Commit-Position: refs/heads/master@{#39311}