Extract a few changes from the Mithril 2 upgrade (#2262)

* Fix closing the composer with ESC key

Regression from #2161.

* Remove obsolete method

Regression from #2162.

* Mark method as protected

* Fade in posts in post stream using CSS

This also avoids a double-fade from the JavaScript code, which was
probably introduced in #2160.

* Fix fadeIn for post stream items

Co-authored-by: Alexander Skvortsov <sasha.skvortsov109@gmail.com>

js/src/forum/components/Composer.js

@@ -82,7 +82,7 @@ export default class Composer extends Component {
     });
 
     // When the escape key is pressed on any inputs, close the composer.
-    this.$().on('keydown', ':input', 'esc', () => this.close());
+    this.$().on('keydown', ':input', 'esc', () => this.state.close());
 
     const handlers = {};