Make collection and collection_from_object methods return an array

This transforms for instance scoped objects into arrays and avoid unneeded queries

[#5958 state:committed]

actionpack/lib/action_view/renderer/partial_renderer.rb

@@ -90,13 +90,14 @@ def render_partial
 
     def collection
       if @options.key?(:collection)
-        @options[:collection] || []
+        collection = @options[:collection]
+        collection.respond_to?(:to_ary) ? collection.to_ary : []
       end
     end
 
     def collection_from_object
       if @object.respond_to?(:to_ary)
-        @object
+        @object.to_ary
       end
     end
 
@@ -163,4 +164,4 @@ def retrieve_variable(path)
       [variable, variable_counter]
     end
   end
-end
+end