message: Fix rounded corners for the formatting toolbar
  The formatting toolbar is meant to have rounded corners like the message action
  bar.
  Fixes
diff: @@ -41,6 +41,18 @@ limitations under the License.
  &:hover {
  border-color: $message-action-bar-hover-border-color;
  }
  +
  + &:first-child {
  + border-radius: 3px 0 0 3px;
  + }
  +
  + &:last-child {
  + border-radius: 0 3px 3px 0;
  + }
  +
  + &:only-child {
  + border-radius: 3px;
  + }
  }
  .mx_MessageComposerFormatBar_button {
  