Included support for property definitions.

[richardspence]

Property definitions weren't being proxied correctly. This walks the prototype chain up the super classes and ensures those properties will be passed to the get handler correctly

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[richardspence]

Fixes #81

[richardspence]

@samthor is this something you can review?

[samthor]

No, I don't work at Google any more.

I'll throw @bramus under the bus?