added "as any" to JSON polyfill for ES6
added "as any" to JSON polyfill for ES6

See issue [#20](https://github.com/JohnWhiteTB/TypedJSON/issues/20)
JohnWhiteTB/TypedJSON,JohnWhiteTB/TypedJSON,JohnWhiteTB/TypedJSON,JohnWeisz/TypedJSON,JohnWeisz/TypedJSON