make tests pass on Ruby 2.2

Apparently we've been using a buggy feature for the past 6 years:

  https://bugs.ruby-lang.org/issues/9593

activerecord/lib/active_record/associations/has_many_association.rb

@@ -71,15 +71,15 @@ def count_records
           [association_scope.limit_value, count].compact.min
         end
 
-        def has_cached_counter?(reflection = reflection)
+        def has_cached_counter?(reflection = reflection())
           owner.attribute_present?(cached_counter_attribute_name(reflection))
         end
 
-        def cached_counter_attribute_name(reflection = reflection)
+        def cached_counter_attribute_name(reflection = reflection())
           options[:counter_cache] || "#{reflection.name}_count"
         end
 
-        def update_counter(difference, reflection = reflection)
+        def update_counter(difference, reflection = reflection())
           if has_cached_counter?(reflection)
             counter = cached_counter_attribute_name(reflection)
             owner.class.update_counters(owner.id, counter => difference)
@@ -98,7 +98,7 @@ def update_counter(difference, reflection = reflection)
         #     it will be decremented twice.
         #
         # Hence this method.
-        def inverse_updates_counter_cache?(reflection = reflection)
+        def inverse_updates_counter_cache?(reflection = reflection())
           counter_name = cached_counter_attribute_name(reflection)
           reflection.klass.reflect_on_all_associations(:belongs_to).any? { |inverse_reflection|
             inverse_reflection.counter_cache_column == counter_name

activesupport/lib/active_support/values/time_zone.rb

@@ -282,7 +282,7 @@ def at(secs)
     #
     #   Time.zone.now               # => Fri, 31 Dec 1999 14:00:00 HST -10:00
     #   Time.zone.parse('22:30:00') # => Fri, 31 Dec 1999 22:30:00 HST -10:00
-    def parse(str, now=now)
+    def parse(str, now=now())
       parts = Date._parse(str, false)
       return if parts.empty?