Properly convert numbers like 1.2345E-4 to Strings

We had an extra "." in the converted number.
Fix loss of precision in Types.toUint16
Fix byte ordering issue in URLCodec#decode
JSON.parse should throw a SyntaxError on unexpected tokens
JSON.stringify was calculating the min # of spaces incorrectly
Make Error's ToString spec happy
Return undefined instead of Java null from JSON.Stringify in certain cases
"foo".concat() should not add "undefined" to the end
Mark builtin String / Function prototype methods as non-constructors
test262 expects Regexp.prototype.compile to exist
Upgrade to an incremental joni to fix nested repeats in regexps

JavaScript does not allow things like /a***/ but joni had no option to
completely disable nested repeats. This incremental version of
dynjs/joni adds that option.
Merge branch 'pr/65'