Bug 1587562 - Disabling browser_favicon.js for fission; r=bradwerth

This is exactly the kind of test that makes no sense once we have finished
the rework of RDM (to be embedded into the browser UI). Indeed, once done,
there won't be a nested iframe in RDM through which we need to make sure
all messages that lead to the tab status/title/icon (and many other things)
are forwarded.

So, because this test currently fails with fission, let's just disable it
for now when in fission mode, and then once the RDM project is done, let's
delete it entirely. No use spending time making it work now if we're going
to remove it later.

Differential Revision: https://phabricator.services.mozilla.com/D57758

--HG--
extra : moz-landing-system : lando

devtools/client/responsive/test/browser/browser.ini

@@ -46,6 +46,7 @@ skip-if = fission # No need to fix this test to run with fission before the new
 [browser_ext_messaging.js]
 tags = devtools webextensions
 [browser_favicon.js]
+skip-if = fission # this test makes no sense once RDM is embedded in the browser UI
 [browser_frame_script_active.js]
 [browser_hide_container.js]
 [browser_in_rdm_pane.js]