Revert "Used any? instead of length call"

Reason: This is slower, and any? is not equivalent in the
general case.

See discussion in https://github.com/rails/rails/pull/3779

This reverts commit 20cbf8ed.

activesupport/lib/active_support/xml_mini/jdom.rb

@@ -70,7 +70,7 @@ def collapse(element)
       hash = get_attributes(element)
 
       child_nodes = element.child_nodes
-      if child_nodes.any?
+      if child_nodes.length > 0
         for i in 0...child_nodes.length
           child = child_nodes.item(i)
           merge_element!(hash, child) unless child.node_type == Node.TEXT_NODE

activesupport/lib/active_support/xml_mini/nokogiri.rb

@@ -26,7 +26,7 @@ def parse(data)
       else
         data.ungetc(char)
         doc = Nokogiri::XML(data)
-        raise doc.errors.first if doc.errors.any?
+        raise doc.errors.first if doc.errors.length > 0
         doc.to_hash
       end
     end