Bug 1878350: Expose empty string to WebDriver to represent "no accessible name", r=Jamie,webdriver-reviewers,whimboo

This revision modifies the WebDriver implementation to return an empty string,
rather than null, for the value of an accessible name, in the event that the
accessible name calculation produces no accessible name. This does not change
what we actually think the accessible name is (null), nor does it change how we
expose it to platforms, but it does bring us in line with other browsers for the
purpose of passing web platform name tests. This revision also removes the 16
expected failures in html "no name" tests.

Differential Revision: https://phabricator.services.mozilla.com/D201633

Author: Nathan LaPre

remote/marionette/actors/MarionetteCommandsChild.sys.mjs

@@ -287,6 +287,11 @@ export class MarionetteCommandsChild extends JSWindowActorChild {
       return null;
     }
 
+    // If name is null (absent), expose the empty string.
+    if (accessible.name === null) {
+      return "";
+    }
+
     return accessible.name;
   }
 

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

@@ -1,48 +1 @@
 [names.html]
-  [address no name]
-    expected: FAIL
-
-  [aside no name]
-    expected: FAIL
-
-  [blockquote no name]
-    expected: FAIL
-
-  [details no name]
-    expected: FAIL
-
-  [figure no name]
-    expected: FAIL
-
-  [footer no name]
-    expected: FAIL
-
-  [form no name]
-    expected: FAIL
-
-  [hgroup no name]
-    expected: FAIL
-
-  [hr no name]
-    expected: FAIL
-
-  [ol no name]
-    expected: FAIL
-
-  [main no name]
-    expected: FAIL
-
-  [menu no name]
-    expected: FAIL
-
-  [nav no name]
-    expected: FAIL
-
-  [search no name]
-    expected: FAIL
-
-  [section no name]
-    expected: FAIL
-
-  [ul no name]
-    expected: FAIL