Bug 1725635 - disable browser_gc_schedule.js on linux_18.04_64_debug for frequent failures. r=intermittent-reviewers,jmaher DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D123306

dom/ipc/tests/browser.ini

@@ -36,6 +36,7 @@ support-files = file_dummy.html
 skip-if =
   verify
   asan  # This test is timing sensitive, failures in asan builds don't indicate a real problem
+  os == 'linux' && bits == 64 && debug # Bug 1725635
 [browser_very_fission.js]
 support-files = file_dummy.html
 run-if = widget == "gtk"