mozilla/jwcrypto — pull request #89 by seanmonstar (2014-07-28 18:18:19+00:00)
Title: no more Strings as Errors!

So we can see stack traces of what part of the assertion sucked.

Also, stops ghosting the real errors with generic `malformed signature`, because https://github.com/mozilla/browserid-verifier/issues/59 wants to know what is actually wrong.