Upgrade to Rails 2.2.0

As a side benefit, fix an (non-user-visible) bug in display_s5().
Also fixed a bug where removing orphaned pages did not expire cached summary pages.

vendor/rails/railties/helpers/performance_test.rb

@@ -0,0 +1,9 @@
+require 'test_helper'
+require 'performance_test_help'
+
+# Profiling results for each test method are written to tmp/performance.
+class BrowsingTest < ActionController::PerformanceTest
+  def test_homepage
+    get '/'
+  end
+end