Fix v8's GN v86 build.

This got out-of-sync with some GYP changes. Also makes it compile on Windows.

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/548713002

Patch from Brett Wilson <brettw@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23770 ce2b1a6d-e550-0410-aec6-3dcde31c8c00