Alter comments on height: auto

Having tested Riot with the middlePanel having a height of 100%, it seems to be OK.

src/skins/vector/css/matrix-react-sdk/structures/_MatrixChat.scss

@@ -90,19 +90,11 @@ limitations under the License.
        */
     overflow-x: auto;
 
-    /* XXX: Hack: apparently if you try to nest a flex-box
-     * within a non-flex-box within a flex-box, the height
-     * of the innermost element gets miscalculated if the
-     * parents are both auto.  Height has to be auto here
-     * for RoomView to correctly fit when the Toolbar is shown.
-     * Ideally we'd launch straight into the RoomView at this
-     * point, but instead we fudge it and make the middlePanel
-     * flex itself.
-     */
     display: flex;
 
     /* To fix https://github.com/vector-im/riot-web/issues/3298 where Safari
-       needed height 100% all the way down to the HomePage.
+       needed height 100% all the way down to the HomePage. Height does not
+       have to be auto, empirically.
     */
     height: 100%;
 }