Match all node types when using node()

Previously this would only match element and text nodes.

lib/oga/xpath/evaluator.rb

@@ -515,9 +515,7 @@ module Oga
         nodes = XML::NodeSet.new
 
         context.each do |node|
-          if node.is_a?(XML::Element) or node.is_a?(XML::Text)
-            nodes << node
-          end
+          nodes << node if node.is_a?(XML::Node)
         end
 
         return nodes

spec/oga/xpath/evaluator/type_tests/node_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe Oga::XPath::Evaluator do
   context 'node() tests' do
     before do
-      @document  = parse('<a><b>foo</b></a>')
+      @document  = parse('<a><b>foo</b><!--foo--><![CDATA[bar]]></a>')
       @evaluator = described_class.new(@document)
     end
 
@@ -24,11 +24,19 @@ describe Oga::XPath::Evaluator do
         @set = @evaluator.evaluate('a/node()')
       end
 
-      it_behaves_like :node_set, :length => 1
+      it_behaves_like :node_set, :length => 3
 
       example 'return the <b> node' do
         @set[0].name.should == 'b'
       end
+
+      example 'return the "foo" comment' do
+        @set[1].text.should == 'foo'
+      end
+
+      example 'return the "bar" CDATA tag' do
+        @set[2].text.should == 'bar'
+      end
     end
 
     context 'matching text nodes' do