In vm, the setter interceptor should not copy a value onto the
sandbox, if setting it on the global object will fail. It will fail if
we are in strict mode and set a value without declaring it.
Fixes: https://github.com/nodejs/node/issues/5344
PR-URL: https://github.com/nodejs/node/pull/7908
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
