Do not load javascripts for disabled plugins (#5103)

* Do not load javascript for disabled plugins

* Appease rubocop

lib/discourse_wrap_plugin_js.rb

@@ -0,0 +1,31 @@
+class DiscourseWrapPluginJS
+  def initialize(options = {}, &block)
+  end
+
+  def self.instance
+    @instance ||= new
+  end
+
+  def self.call(input)
+    instance.call(input)
+  end
+
+  # Add stuff around javascript
+  def call(input)
+    path = input[:environment].context_class.new(input).pathname.to_s
+    data = input[:data]
+
+    # Only apply to plugin paths
+    return data unless (path =~ /\/plugins\//)
+
+    # Find the folder name of the plugin
+    folder_name = path[/\/plugins\/(\S+?)\//, 1]
+
+    # Lookup plugin name
+    plugin = Discourse.plugins.find { |p| p.path =~ /\/plugins\/#{folder_name}\// }
+    plugin_name = plugin.name
+
+    "Discourse._registerPluginScriptDefinition('#{plugin_name}', function(){#{data}}); \n"
+  end
+
+end