ooh, nice! missed that part.
Did you consider having that pull from a CDN rather than locally? Reason being, any updates to said polyfills will require you to deploy an update. Whereas if you have a template tag to pull from a CDN, you can have your users specify the version if necessary and pull the latest by default. Would be one less thing you have to worry about maintaining.
On current browsers, this file does nothing, preferring the built-in JSON object. There is no reason to use this file unless fate compels you to support IE8, which is something that no one should ever have to do again.
Other than that, the lib looks pretty good to me. </thumbs-up>