I think we're on the same page, @dmethvin...
* Assume string input; any behavior from non-strings—including successes—will be undefined
  * Except [`null`](https://github.com/gibson042/jquery/blob/079158994ec1f6883afece7bbc45094e00700556/test/unit/core.js#L1344)? :cry:
* Tolerate lax behavior from native parsers to always use `JSON.parse` when possible
  * Be lax ourselves with respect to leading zeroes and control characters, saving 15-20 bytes
  * Leave the commented-out edge case tests for posterity