Do not count search route as compose being mounted in web UI (#7372)

Fix #7144

app/javascript/mastodon/features/compose/index.js

@@ -43,12 +43,20 @@ export default class Compose extends React.PureComponent {
   };
 
   componentDidMount () {
+    const { isSearchPage } = this.props;
+
+    if (!isSearchPage) {
       this.props.dispatch(mountCompose());
     }
+  }
 
   componentWillUnmount () {
+    const { isSearchPage } = this.props;
+
+    if (!isSearchPage) {
       this.props.dispatch(unmountCompose());
     }
+  }
 
   onFocus = () => {
     this.props.dispatch(changeComposing(true));