JSON.parse("-0 ") should give the same result as JSON.parse("-0"), but where the latter correctly returns -0.0, the former returns positive 0.0.
This is fixed as of rev. 246299: negative zero surrounded by whitespace is parsed correctly. To prevent regressions, I am adding a few test cases to Test262: https://github.com/tc39/test262/pull/2196 (file: text-negative-zero.js)