CommandRecorder should delegate in method_missing where possible. Fix…

…es some tests in migration_test.rb under mysql. The problem was introduced in c278a2c.

activerecord/lib/active_record/migration/command_recorder.rb

@@ -97,7 +97,11 @@ def invert_add_timestamps(args)
       # This will ensure that IrreversibleMigration is raised when the corresponding
       # invert_method does not exist while the migration is rolled back.
       def method_missing(method, *args, &block)
-        record(method, args)
+        if delegate.respond_to?(method)
+          delegate.send(method, *args, &block)
+        else
+          record(method, args)
+        end
       end
 
     end

activerecord/test/cases/migration/command_recorder_test.rb

@@ -31,7 +31,12 @@ def create_table(name); end
         assert_equal [[:create_table, [:horses]]], recorder.commands
       end
 
-      def test_unknown_commands_raise_exception
+      def test_unknown_commands_delegate
+        recorder = CommandRecorder.new(stub(:foo => 'bar'))
+        assert_equal 'bar', recorder.foo
+      end
+
+      def test_unknown_commands_raise_exception_if_they_cannot_delegate
         @recorder.record :execute, ['some sql']
         assert_raises(ActiveRecord::IrreversibleMigration) do
           @recorder.inverse