Preload tinymce assets

Tinymce loads the editor content css and its plugins on initialize.
Since we init tinymce only when its visible it takes long to init the
editor. Using browser preload features to make sure the assets
are already loaded.

app/views/alchemy/admin/pages/edit.html.erb

@@ -2,6 +2,20 @@
 
 <% content_for(:main_menu_style) { 'collapsed-menu' } %>
 
+<% content_for :stylesheets do %>
+  <link rel="preload" href="/assets/tinymce/skins/alchemy/skin.min.css" as="style" />
+  <link rel="preload" href="/assets/tinymce/skins/alchemy/content.min.css" as="style" />
+  <% if Alchemy::Tinymce.init[:content_css] %>
+    <link rel="preload" href="<%= Alchemy::Tinymce.init[:content_css] %>" as="style" />
+  <% end %>
+<% end %>
+
+<% content_for :javascripts do %>
+  <% Alchemy::Tinymce.eagerload_plugins.each do |plugin| %>
+    <link rel="preload" href="/assets/tinymce/plugins/<%= plugin %>/plugin.min.js" as="script">
+  <% end %>
+<% end %>
+
 <% content_for(:toolbar) do %>
 <div class="toolbar_buttons">
   <div class="button_with_label">

lib/alchemy/tinymce.rb

@@ -4,13 +4,14 @@ module Alchemy
   module Tinymce
     mattr_accessor :languages, :plugins
 
-    @@plugins = %w[alchemy_link anchor autoresize charmap code directionality fullscreen hr link lists paste tabfocus table]
+    DEFAULT_PLUGINS = %w[anchor charmap code directionality fullscreen hr link lists paste tabfocus table]
+
+    @@plugins = DEFAULT_PLUGINS + %w[alchemy_link]
     @@init = {
       skin: "alchemy",
       width: "auto",
       resize: true,
-      autoresize_min_height: "105",
-      autoresize_max_height: "480",
+      min_height: 220,
       menubar: false,
       statusbar: true,
       toolbar: [
@@ -33,6 +34,10 @@ def init=(settings)
       def init
         @@init
       end
+
+      def eagerload_plugins
+        @@plugins - DEFAULT_PLUGINS
+      end
     end
   end
 end