push up bind params on "simple" subquery calculations

bind parameters we not being propogated to simple subquery calculation
calls. This fixes it

activerecord/lib/active_record/relation/calculations.rb

@@ -242,7 +242,7 @@ module ActiveRecord
         return 0 if relation.limit_value == 0
 
         query_builder = build_count_subquery(relation, column_name, distinct)
-        bind_values = relation.bind_values
+        bind_values = query_builder.bind_values + relation.bind_values
       else
         column = aggregate_column(column_name)
 
@@ -389,9 +389,11 @@ module ActiveRecord
 
       aliased_column = aggregate_column(column_name == :all ? 1 : column_name).as(column_alias)
       relation.select_values = [aliased_column]
-      subquery = relation.arel.as(subquery_alias)
+      arel = relation.arel
+      subquery = arel.as(subquery_alias)
 
       sm = Arel::SelectManager.new relation.engine
+      sm.bind_values = arel.bind_values
       select_value = operation_over_aggregate_column(column_alias, 'count', distinct)
       sm.project(select_value).from(subquery)
     end

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -43,12 +43,18 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :categories, :companies, :developers, :projects,
            :developers_projects, :topics, :authors, :comments,
            :people, :posts, :readers, :taggings, :cars, :essays,
-           :categorizations, :jobs
+           :categorizations, :jobs, :tags, :posts
 
   def setup
     Client.destroyed_client_ids.clear
   end
 
+  def test_sti_subselect_count
+    tag = Tag.first
+    len = Post.tagged_with(tag.id).limit(10).size
+    assert_operator len, :>, 0
+  end
+
   def test_anonymous_has_many
     developer = Class.new(ActiveRecord::Base) {
       self.table_name = 'developers'