fix styling of clearButton when its not there

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

res/css/structures/_TagPanel.scss

@@ -25,7 +25,7 @@ limitations under the License.
     justify-content: space-between;
 }
 
-.mx_TagPanel .mx_TagPanel_clearButton {
+.mx_TagPanel .mx_TagPanel_clearButton_container {
     /* Constant height within flex mx_TagPanel */
     height: 70px;
     width: 60px;

src/components/structures/TagPanel.js

@@ -127,7 +127,9 @@ const TagPanel = React.createClass({
         }
 
         return <div className="mx_TagPanel">
+            <div className="mx_TagPanel_clearButton_container">
                 { clearButton }
+            </div>
             <div className="mx_TagPanel_divider" />
             <GeminiScrollbarWrapper
                 className="mx_TagPanel_scroller"