Ensure that changing the selected item doesn't affect the size of the Picker (#334)

Co-authored-by: Robert Snow <rsnow@adobe.com>
Co-authored-by: Danni <drobinson@livefyre.com>

Author: 3 people

packages/@adobe/spectrum-css-temp/components/dropdown/index.css

@@ -27,6 +27,9 @@ governing permissions and limitations under the License.
   inline-size: var(--spectrum-dropdown-width);
   min-inline-size: var(--spectrum-dropdown-min-width);
 
+  /* Ensure that changing the selected item doesn't affect the size of the dropdown and its parents */
+  contain: size;
+
   /* Hack to enable select-powered Dropdowns */
   select {
     appearance: none;