Update resources.
Import some of Mozilla's Crypto API utilities.

All code is "PD Test Code" as defined by
<https://www.mozilla.org/MPL/license-policy.html#Licensing_of_Mozilla_Code>
and is thus used here under the Creative Commons Public Domain Dedication.

Contributors to test-vectors.js:
  David Keeler <dkeeler@mozilla.com>
  Ed Morley <emorley@mozilla.com>
  Richard Barnes <rbarnes@mozilla.com>
  Ryan VanderMeulen <ryanvm@gmail.com>
  Tim Taubert <ttaubert@mozilla.com>

Contributors to util.js:
  Richard Barnes <rbarnes@mozilla.com>
Avoid fat arrows in util.js.

They are not yet widely supported.
Add a test for the Diffie-Hellman algorithm in the Crypto API.

This test is based on Mozilla's test_WebCrypto_DH.html.

That test is "PD Test Code" as defined by
<https://www.mozilla.org/MPL/license-policy.html#Licensing_of_Mozilla_Code>
and is thus used here under the Creative Commons Public Domain Dedication.

Contributors to test_WebCrypto_DH.html:
  Tim Taubert <ttaubert@mozilla.com>