Bug 1854538 - Temporarily fail-if some Tier 2 a11y_checks for UI Widgets. r=mconley

We are working on [enabling Tier 2 a11y-checks to ensure our products have basic accessibility built-in (bug 1692110)](https://bugzilla.mozilla.org/show_bug.cgi?id=1692110) and before that, we need to prepare the existing code base. While we triage and investigate existent tests that would fail once the a11y-checks are enabled in the CI, we are going to fail-if the failing tests altogether and then handle each one of them individually.

This task is to add `fail-if` condition of the failing tests while we continue investigation into the reasons these tests failed and to be able to backtrack these tests once they're resolved.

Related bugs:
- Disabling tests: meta bug 1848402
- Investigation and remediation for components with disabled tests: meta bugs 1848394 and 1854227, component-specific meta bug 1854539
- Explore capturing click events for a11y_checks: bug 1692110

Depends on D188926

Differential Revision: https://phabricator.services.mozilla.com/D188927

toolkit/content/tests/browser/browser.toml

@@ -25,14 +25,17 @@ support-files = [
 skip-if = ["tsan"] # Bug 1804081
 
 ["browser_about_networking.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked #category-dns may not be focusable
 skip-if = ["socketprocess_networking"]
 
 ["browser_autoscroll_disabled.js"]
 skip-if = ["true"] # Bug 1312652
 
 ["browser_autoscroll_disabled_on_editable_content.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked browser may not be focusable
 
 ["browser_autoscroll_disabled_on_links.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked browser may not be focusable
 
 ["browser_bug295977_autoscroll_overflow.js"]
 skip-if = [
@@ -59,12 +62,14 @@ support-files = ["file_document_open_audio.html"]
 ["browser_bug1693577.js"]
 
 ["browser_cancel_starting_autoscrolling_requested_by_background_tab.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked tabbrowser-tabpanels may not be accessible
 
 ["browser_charsetMenu_disable_on_ascii.js"]
 
 ["browser_charsetMenu_swapBrowsers.js"]
 
 ["browser_click_event_during_autoscrolling.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked browser may not be accessible
 
 ["browser_contentTitle.js"]
 
@@ -136,6 +141,7 @@ skip-if = ["os == 'linux' && bits == 64 && os_version == '18.04'"] # Bug 1614739
 ["browser_keyevents_during_autoscrolling.js"]
 
 ["browser_label_textlink.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked label#textlink-text may not be focusable
 https_first_disabled = true
 
 ["browser_license_links.js"]
@@ -186,6 +192,7 @@ support-files = [
 skip-if = ["true"] # Bug ?????? - test directly manipulates content (gBrowser.contentDocument.getElementById("postForm").submit();)
 
 ["browser_starting_autoscroll_in_about_content.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked body.wide-container may not be accessible
 
 ["browser_suspend_videos_outside_viewport.js"]
 support-files = [

toolkit/content/tests/browser/datetime/browser.toml

@@ -9,6 +9,7 @@ skip-if = [
 ]
 
 ["browser_datetime_datepicker.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked td.outside may not be accessible
 # This file was skipped before new tests were written based on it in Bug 1676068
 skip-if = [
   "tsan", # Frequently times out on TSan
@@ -45,6 +46,7 @@ skip-if = [
 ]
 
 ["browser_datetime_datepicker_min_max.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked TD may not be accessible
 skip-if = [
   "tsan", # Frequently times out on TSan
   "os == 'win' && asan", # fails on asan
@@ -59,6 +61,7 @@ skip-if = [
 ]
 
 ["browser_datetime_datepicker_mousenav.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked td.weekend.outside may not be accessible
 skip-if = [
   "tsan", # Frequently times out on TSan
   "os == 'win' && asan", # fails on asan
@@ -76,6 +79,7 @@ skip-if = [
 # do not skip
 
 ["browser_datetime_toplevel.js"]
+fail-if = ["a11y_checks"] # Bug 1854538 clicked input may not be accessible
 
 ["browser_spinner.js"]
 skip-if = [