v8::DontDelete is set for Unforgeable properties, so just not setting PROHIBITS_OVERWRITING should be enough.
The secondary "feature" of not allowing accessors to be installed in extending objects is incorrect and confusing, given that it only applies to accessors but not to regular properties:
Object.defineProperty({__proto__:window}, "location", { value: 10 })
works where
Object.defineProperty({__proto__:window}, "location", { get: function() {} })
doesn't work.
LOG=y
R=dcarney@chromium.org
Review URL: https://codereview.chromium.org/306203002
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21596 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
60a71d8a8c