Ensure SAX after_element receives meaningful args

This changes the behaviour of after_element when parsing documents using the SAX
parsing API. Previously it would always receive a nil argument, which is kinda
pointless. This commit changes that by making sure it receives a namespace name
(if any) and the element name.

This fixes #54.

spec/oga/xml/sax_parser_spec.rb

@@ -3,11 +3,16 @@ require 'spec_helper'
 describe Oga::XML::SaxParser do
   before do
     @handler = Class.new do
-      attr_reader :name
+      attr_reader :name, :after_namespace, :after_name
 
       def on_element(namespace, name, attrs = {})
         @name = name
       end
+
+      def after_element(namespace, name)
+        @after_namespace = namespace
+        @after_name      = name
+      end
     end
   end
 
@@ -26,6 +31,16 @@ describe Oga::XML::SaxParser do
     handler.name.should == 'foo'
   end
 
+  example 'always pass element names to after_element' do
+    handler = @handler.new
+    parser  = described_class.new(handler, '<namespace:foo />')
+
+    parser.parse
+
+    handler.after_name.should      == 'foo'
+    handler.after_namespace.should == 'namespace'
+  end
+
   example 'ignore callbacks that are not defined in the handler' do
     parser = described_class.new(@handler.new, '<!--foo-->')