Apply more general fix for base avatar regressions (#10045)

Author: t3chguy

res/css/structures/_UserMenu.pcss

@@ -25,8 +25,6 @@ limitations under the License.
 
         .mx_UserMenu_userAvatar {
             position: relative;
-            /* without this a default avatar will cause this to be 4px oversized and out of alignment */
-            display: inherit;
 
             .mx_BaseAvatar {
                 pointer-events: none; /* makes the avatar non-draggable */

res/css/views/avatars/_BaseAvatar.pcss

@@ -16,16 +16,7 @@ limitations under the License.
 
 .mx_BaseAvatar {
     position: relative;
-    /* In at least Firefox, the case of relative positioned inline elements */
-    /* (such as mx_BaseAvatar) with absolute positioned children (such as */
-    /* mx_BaseAvatar_initial) is a dark corner full of spider webs. It will give */
-    /* different results during full reflow of the page vs. incremental reflow */
-    /* of small portions. While that's surely a browser bug, we can avoid it by */
-    /* using `inline-block` instead of the default `inline`. */
-    /* https://github.com/vector-im/element-web/issues/5594 */
-    /* https://bugzilla.mozilla.org/show_bug.cgi?id=1535053 */
-    /* https://bugzilla.mozilla.org/show_bug.cgi?id=255139 */
-    display: inline-block;
+    display: block;
     user-select: none;
 
     &.mx_RoomAvatar_isSpaceRoom {