revert dd08f53756 - do this in JS instead

src/skins/vector/css/organisms/RoomView.css

@@ -91,8 +91,8 @@ limitations under the License.
     overflow: auto;
     border-bottom: 1px solid #eee;
 
-    -webkit-flex: 0 1 auto;
-    flex: 0 1 auto;
+    -webkit-flex: 0 0 auto;
+    flex: 0 0 auto;
 }
 
 .mx_RoomView_messagePanel {