Sprockets legacy processor interface

Two arguments get passed in, so we need to arguments in the interface.

Author: schneems

test/fixtures/scss_project/config/initializers/postprocessor.rb

@@ -5,7 +5,7 @@ def initialize(filename, &block)
     @source   = block.call
   end
 
-  def render(context)
+  def render(context, _)
     self.class.run(@source)
   end