ruffle: fix issue with ruffle falsely triggering keyboard shortcuts.

Fix issue mentioned in 55980c6fb with Javascript spazzing out on Flash
posts and randomly triggering keyboard shortcuts.

The bug was calling `javascript_pack_tag` twice. This caused the
runtime Javascript chunk to be loaded twice, caused a lot of Javascript
errors that somehow resulted in keyboard shortcuts being triggered.

The fix is to combine both calls into `javascript_pack_tag "application", "flash"`.

hxxps://github.com.rails.webpacker.issues.2932

app/javascript/src/javascripts/posts.js.erb

@@ -35,6 +35,7 @@ Post.initialize_all = function() {
     this.initialize_post_image_resize_links();
     this.initialize_recommended();
     this.initialize_ugoira_player();
+    this.initialize_ruffle_player();
   }
 
   if ($("#c-posts #a-show, #c-uploads #a-new").length) {
@@ -380,6 +381,19 @@ Post.initialize_ugoira_player = function() {
   }
 };
 
+Post.initialize_ruffle_player = function() {
+  if (!window.RufflePlayer) {
+    return;
+  }
+
+  let ruffle = window.RufflePlayer.newest();
+  let player = ruffle.createPlayer();
+  let $container = $(".ruffle-container[data-swf]");
+  let src = $container.attr("data-swf");
+  $container.get(0).appendChild(player);
+  player.load(src);
+};
+
 Post.resize_ugoira_controls = function() {
   var $img = $("#image");
   var width = Math.max($img.width(), 350);