And some bugs in JSONFunctions.

typeof JSON.parse('{}',function(){})
=> expected "undefined" instead of "object"
=> JSONFunctions#walk() looks a bit wrong.

Object.defineProperty(Object.prototype,"",{set:
function(v){print("called set")}})
JSON.parse('{}',function(){})
=> should not call the setter (use [[DefineOwnProperty]] instead of [[Put]])

Object.defineProperty(Object.prototype,"foo",{set:
function(v){print("called set")}})
JSON.parse('{"foo": 1}')
=> should not call the setter (use [[DefineOwnProperty]] instead of [[Put]])

- André