URL tests from https://github.com/annevk/url/
new test for setRequestHeader() with value arguments empty string, null, undefined
Remove some tests that do not add anything over Aryeh's reflection tests.
Merge pull request #389 from Ms2ger/obsolete-tests

Remove some tests that do not add anything over Aryeh's reflection tests.
Merge pull request #385 from w3c/add_setrequestheader_empty_test

new test for setRequestHeader() with value arguments empty string, null,...
Fix issues: https://critic.hoppipolla.co.uk/r/300
Merge pull request #319 from annevk/url

URL tests from https://github.com/annevk/url/