Bug 1858051: Fix ComputedARIARole for <input type="search">, r=Jamie

The markup <input type="search"> will report a ComputedARIARole of "textbox,"
which isn't correct - it should return "searchbox." To address this issue, this
revision implements a change to ComputedARIARole for searchboxes, checking
IsSearchbox() and returning the searchbox atom if so. This revision also enables
the previously expected-failure relevant web platform test, since we now pass it.

Differential Revision: https://phabricator.services.mozilla.com/D200235

accessible/basetypes/Accessible.cpp

@@ -572,12 +572,14 @@ nsStaticAtom* Accessible::ComputedARIARole() const {
       (roleMap->roleRule == kUseNativeRole || roleMap->IsOfType(eLandmark) ||
        roleMap->roleAtom == nsGkAtoms::alertdialog ||
        roleMap->roleAtom == nsGkAtoms::feed ||
-       roleMap->roleAtom == nsGkAtoms::rowgroup ||
-       roleMap->roleAtom == nsGkAtoms::searchbox)) {
+       roleMap->roleAtom == nsGkAtoms::rowgroup)) {
     // Explicit ARIA role (e.g. specified via the role attribute) which does not
     // map to a unique Gecko role.
     return roleMap->roleAtom;
   }
+  if (IsSearchbox()) {
+    return nsGkAtoms::searchbox;
+  }
   role geckoRole = Role();
   if (geckoRole == roles::LANDMARK) {
     // Landmark role from native markup; e.g. <main>, <nav>.

testing/web-platform/meta/html-aam/roles.html.ini

@@ -1,7 +1,4 @@
 [roles.html]
-  [el-input-search]
-    expected: FAIL
-
   [el-em]
     expected: FAIL