fix(material-experimental/mdc-tooltip): add mdc-tooltip__surface-animation class as MDC is splitting up animation and visual styles

Author: annieyw

src/material-experimental/mdc-tooltip/tooltip.html

@@ -4,5 +4,5 @@
   [@state]="_visibility"
   (@state.start)="_animationStart()"
   (@state.done)="_animationDone($event)">
-  <div class="mdc-tooltip__surface">{{message}}</div>
+  <div class="mdc-tooltip__surface mdc-tooltip__surface-animation">{{message}}</div>
 </div>