Bug 1606796 - Make tab focus tests for shadow DOM work on Mac; r=smaug

The behavior of focus navigation on Mac depends on OS setting, but we could also change it by setting accessibility.tabfocus to 7, like other tests do.

Differential Revision: https://phabricator.services.mozilla.com/D58595

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

dom/base/test/mochitest.ini

@@ -619,7 +619,6 @@ support-files = file_bug1100912.html
 [test_bug1406102.html]
 [test_bug1421568.html]
 [test_bug1453693.html]
-skip-if = os == "mac" # Different tab focus behavior on mac
 [test_bug1472427.html]
 [test_bug1499169.html]
 skip-if = toolkit == 'android' # Timeouts on android due to page closing issues with embedded pdf
@@ -666,7 +665,6 @@ skip-if = (toolkit == 'android') # Android: Bug 1465387
 [test_find_nac.html]
 skip-if = (toolkit == 'android') # Android: Bug 1465387
 [test_focus_shadow_dom_root.html]
-skip-if = os == "mac" # Different tab focus behavior on mac
 [test_getAttribute_after_createAttribute.html]
 [test_getElementById.html]
 [test_getTranslationNodes.html]

dom/base/test/test_bug1453693.html

@@ -14,7 +14,11 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1453693
 
   SimpleTest.waitForExplicitFinish();
 
-  function runTests() {
+  async function runTests() {
+    // Enable Full Keyboard Access emulation on Mac.
+    if (navigator.platform.indexOf("Mac") === 0) {
+      await SpecialPowers.pushPrefEnv({"set": [["accessibility.tabfocus", 7]]});
+    }
     win = window.open("file_bug1453693.html", "", "width=300, height=300");
   }
 

dom/base/test/test_focus_shadow_dom_root.html

@@ -15,7 +15,12 @@
   document.appendChild(host);
 
   SimpleTest.waitForExplicitFinish();
-  SimpleTest.waitForFocus(function() {
+  SimpleTest.waitForFocus(async function() {
+    // Enable Full Keyboard Access emulation on Mac.
+    if (navigator.platform.indexOf("Mac") === 0) {
+      await SpecialPowers.pushPrefEnv({"set": [["accessibility.tabfocus", 7]]});
+    }
+
     is(document.documentElement, host, "Host is the document element");
     host.offsetTop;
     synthesizeKey("KEY_Tab");