Reviewed by Maciej.

    Reviewed by Maciej.

        - Finalized exception handling in the API.

        setProperty can throw because it throws for built-in arrays. getProperty
        and deleteProperty can throw because setProperty can throw and we want
        to be consistent, and also because they seem like "actions." callAsFunction,
        callAsConstructor, and hasInstance can throw, because they caan throw for
        all built-ins.

        toBoolean can't throw because it's defined that way in the spec.

        - Documented that toBoolean and toObject can't be overridden by custom
        objects because they're defined that way in the spec.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@15443 268f45cc-cd09-0410-ab3c-d52691b4dbfc