use a queue rather than a list. fixes rails#12069

Author: tenderlove

activesupport/lib/active_support/notifications/fanout.rb

@@ -108,7 +108,7 @@ def matches?(subscriber_or_name)
 
         class Timed < Evented
           def initialize(pattern, delegate)
-            @timestack = []
+            @timestack = Queue.new
             super
           end