document.rb in opal-jquery-0.3.0.beta1

- old
+ new

@@ -1,9 +1,12 @@
+require 'opal-jquery/constants'
 require 'opal-jquery/element'
 
 Document = Element.find(`document`)
 
 class << Document
+  `var $ = #{JQUERY_SELECTOR.to_n}` # cache $ for SPEED
+
   def ready?(&block)
     `$(#{ block })` if block
   end
 
   def title