message: Add optional rounded chevron for tooltip
  We'd like to have a rounded point on the chevron for an extra level of polish.
  This implements that look for browsers that support `clip-path`.
  Part of
diff: @@ -55,6 +55,21 @@ limitations under the License.
  border-right: 8px solid transparent;
  }
  +// Adapted from https://codyhouse.co/blog/post/css-rounded-triangles-with-clip-path
  +// by Sebastiano Guerriero (@guerriero_se)
  +@supports (clip-path: polygon(0% 0%, 100% 100%, 0% 100%)) {
  + .mx_InteractiveTooltip_chevron_top {
  + height: 16px;
  + width: 16px;
  + background-color: inherit;
  + border: none;
  + clip-path: polygon(0% 0%, 100% 100%, 0% 100%);
  + transform: rotate(135deg);
  + border-radius: 0 0 0 3px;
  + top: calc(-8px / 1.414); // sqrt(2) because of rotation
  + }
  +}
  +
  .mx_InteractiveTooltip.mx_InteractiveTooltip_withChevron_bottom {
  bottom: 10px; // 8px chevron + 2px spacing
  }
  @@ -69,3 +84,18 @@ limitations under the License.
  border-top: 8px solid $interactive-tooltip-bg-color;
  border-right: 8px solid transparent;
  }
  +
  +// Adapted from https://codyhouse.co/blog/post/css-rounded-triangles-with-clip-path
  +// by Sebastiano Guerriero (@guerriero_se)
  +@supports (clip-path: polygon(0% 0%, 100% 100%, 0% 100%)) {
  + .mx_InteractiveTooltip_chevron_bottom {
  + height: 16px;
  + width: 16px;
  + background-color: inherit;
  + border: none;
  + clip-path: polygon(0% 0%, 100% 100%, 0% 100%);
  + transform: rotate(-45deg);
  + border-radius: 0 0 0 3px;
  + bottom: calc(-8px / 1.414); // sqrt(2) because of rotation
  + }
  +}
  