Fix cross-origin integrity (#1871)

See <https://glitch.social/users/bea/updates/434>

app/views/home/index.html.haml

 - content_for :header_tags do
   %script#initial-state{:type => 'application/json'}!= json_escape(render(file: 'home/initial_state', formats: :json))
 
-  = javascript_include_tag 'application', integrity: true
+  = javascript_include_tag 'application', integrity: true, crossorigin: 'anonymous'
 
 = react_component 'Mastodon', default_props, class: 'app-holder', prerender: false

app/views/layouts/admin.html.haml

 - content_for :header_tags do
-  = javascript_include_tag 'application_public', integrity: true
+  = javascript_include_tag 'application_public', integrity: true, crossorigin: 'anonymous'
 
 - content_for :content do
   .admin-wrapper

app/views/layouts/auth.html.haml

 - content_for :header_tags do
-  = javascript_include_tag 'application_public', integrity: true
+  = javascript_include_tag 'application_public', integrity: true, crossorigin: 'anonymous'
 
 - content_for :content do
   .container

app/views/layouts/embedded.html.haml

@@ -3,6 +3,6 @@
   %head
     %meta{:charset => 'utf-8'}/
     = stylesheet_link_tag 'application', media: 'all'
-    = javascript_include_tag 'application_public', integrity: true
+    = javascript_include_tag 'application_public', integrity: true, crossorigin: 'anonymous'
   %body.embed
     = yield

app/views/layouts/public.html.haml

 - content_for :header_tags do
-  = javascript_include_tag 'application_public', integrity: true
+  = javascript_include_tag 'application_public', integrity: true, crossorigin: 'anonymous'
 
 - content_for :content do
   .container= yield