Add support for /groups

The /groups url seems to work in PolyGerrit so there's no reason
to blacklist it.

Change-Id: I78bffe2796e1953efbbbf9d45479a1d7bd918928
(cherry picked from commit a463d75a55)

polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.js

@@ -277,8 +277,7 @@
       if (!account) { return; }
 
       this.$.restAPI.getPreferences().then(prefs => {
-        this._userLinks =
-            prefs.my.map(this._fixCustomMenuItem).filter(this._isSupportedLink);
+        this._userLinks = prefs.my.map(this._fixCustomMenuItem);
       });
     },
 
@@ -313,11 +312,6 @@
       return linkObj;
     },
 
-    _isSupportedLink(linkObj) {
-      // Groups are not yet supported.
-      return !linkObj.url.startsWith('/groups');
-    },
-
     _generateSettingsLink() {
       return this.getBaseUrl() + '/settings/';
     },

polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.html

@@ -91,17 +91,6 @@ limitations under the License.
       ]);
     });
 
-    test('filter unsupported urls', () => {
-      assert.deepEqual([
-        {url: '/c/331788/'},
-        {url: '/groups/self'},
-        {url: 'https://awesometown.com/#hashyhash'},
-      ].filter(element._isSupportedLink), [
-        {url: '/c/331788/'},
-        {url: 'https://awesometown.com/#hashyhash'},
-      ]);
-    });
-
     test('user links', () => {
       const defaultLinks = [{
         title: 'Faves',