FEATURE: upgrade sprockets to latest stable

This unlocks Rails upgrades, so we can now upgrade to latest Rails

lib/source_url.rb

@@ -1,6 +1,15 @@
 class SourceURL < Tilt::Template
   self.default_mime_type = 'application/javascript'
 
+  def self.call(input)
+    filename = input[:filename]
+    source = input[:data]
+    context = input[:environment].context_class.new(input)
+
+    result = new(filename){source}.render(context)
+    context.metadata.merge(data: result)
+  end
+
   def prepare
   end