Avoid two-step rendering of statuses as much as possible

Cache width shared by Video player, MediaGallery and Cards at the
ScrollableList level, pass it down through StatusList and Notifications.

app/javascript/flavours/glitch/components/scrollable_list.js

@@ -40,6 +40,7 @@ export default class ScrollableList extends PureComponent {
 
   state = {
     fullscreen: null,
+    cachedMediaWidth: 300,
   };
 
   intersectionObserverWrapper = new IntersectionObserverWrapper();
@@ -141,6 +142,10 @@ export default class ScrollableList extends PureComponent {
     this.setScrollTop(newScrollTop);
   }
 
+  cacheMediaWidth = (width) => {
+    if (width && this.state.cachedMediaWidth != width) this.setState({ cachedMediaWidth: width });
+  }
+
   getSnapshotBeforeUpdate (prevProps, prevState) {
     const someItemInserted = React.Children.count(prevProps.children) > 0 &&
       React.Children.count(prevProps.children) < React.Children.count(this.props.children) &&
@@ -252,7 +257,12 @@ export default class ScrollableList extends PureComponent {
                 intersectionObserverWrapper={this.intersectionObserverWrapper}
                 saveHeightKey={trackScroll ? `${this.context.router.route.location.key}:${scrollKey}` : null}
               >
-                {React.cloneElement(child, {getScrollPosition: this.getScrollPosition, updateScrollBottom: this.updateScrollBottom})}
+                {React.cloneElement(child, {
+                  getScrollPosition: this.getScrollPosition,
+                  updateScrollBottom: this.updateScrollBottom,
+                  cachedMediaWidth: this.state.cachedMediaWidth,
+                  cacheMediaWidth: this.cacheMediaWidth,
+                })}
               </IntersectionObserverArticleContainer>
             ))}