v8: let Object.defineProperty work with process.env
This fixes #2998 (closed).
This is only a back port to v3.x since the bug will not emerge in v4.x. It turned out that the v8 team encountered a similar bug regarding window.localStorage
in Chrome and landed a patch in Jun which is consequently applied into Node 4.x.
https://codereview.chromium.org/1180073002
However the patch is too big to back port to v3.x. I made a minimal version and therefore come this PR.