A small Cross-Origin Opener Policy test page

Allowed HTTP parameters:
`coop': The Cross-Origin-Opener-Policy for this window (default: none)
`openee_host': The hostname of the popup (default: victim.arturjanc.com)

Current config: coop=same-origin; openee_host=arturjanc.com; current host=arturjanc.com

Standard tests

Test: Invalid COOP header.
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=zzz&openee_host=www.arturjanc.com
Expected: Both green (can read window.name and receive postMessage)
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD;

Test: same-origin COOP & same-origin window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-origin&openee_host=arturjanc.com
Expected: Both green (can read window.name and receive postMessage)
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD

Test: same-origin COOP & same-site window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-origin&openee_host=www.arturjanc.com
Expected: Both red (no access)
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD

Test: same-site COOP & same-site window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-site&openee_host=www.arturjanc.com
Expected: Both green
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD

Test: same-site COOP & same-origin window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-site&openee_host=arturjanc.com
Expected: Both green
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD

Test: same-origin COOP & cross-site window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-origin&openee_host=example.org
Expected: New window will have window.opener == null
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD

Test: same-site COOP & cross-site window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-site&openee_host=example.org
Expected: New window will have window.opener == null
Actual: Firefox Nightly 68.0a1 (2019-05-07): GOOD

Test: same-origin COOP with unsafe-allow-outgoing & cross-site window
URL: https://arturjanc.com/cgi-bin/coop/index-with-coop.py?coop=same-origin unsafe-allow-outgoing&openee_host=example.org
Expected: New window will have window.opener.
Actual: Firefox Nightly 68.0a1 (2019-05-07): BAD