Audit privacytests.org for WPT coverage

[ChrisC]

PrivacyTests.org is an open-source initiative that subjects popular web browsers to a suite of automated tests. These tests are designed to audit web browsers' privacy properties in an unbiased manner. The results of the tests are made public to help users make an informed choice about which browser to use, and to encourage browser makers to fix leaks of private user data.

For the purposes of this investigation area, we should audit privacytests.org for tests that might be added to WPT for purposes of tracking interoperability.