[[DefineOwnProperty]] should always return true/false (or throw an exception), never undefined.

[[DefineOwnProperty]] should always return true/false (or throw an exception), never undefined.

Note that this is not an observable behavior, but following the principle of
least surprise, we should follow the spec. Additional (extremely tiny) bonus:
Some ICs see fewer values => better code.
Committed: http://code.google.com/p/v8/source/detail?r=9706

[Michael Starzinger, 2011-10-19 13:20:30]

LGTM.