Prevent breaking leading xml tag

source/CsQuery.Tests/Core/OutputFormatters/FormatDefault.cs

@@ -0,0 +1,22 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using NUnit.Framework;
+using Assert = NUnit.Framework.Assert;
+
+namespace CsQuery.Tests.Core.OutputFormatters_
+{
+    [TestFixture, TestClass]
+    class FormatDefault
+    {
+        [Test, TestMethod]
+        public void RenderLeadingXmlTag()
+        {
+            const string XmlTag = @"<?xml version=""1.0"" encoding=""UTF-8""?>";
+
+            var formatter = new Output.FormatDefault();
+            var comment = new CsQuery.Implementation.DomComment(XmlTag);
+            var actual = formatter.Render(comment);
+
+            Assert.AreEqual(XmlTag, actual, "FormatDefault should not change leading xml tag.");
+        }
+    }
+}

source/CsQuery.Tests/Csquery.Tests.csproj

@@ -96,6 +96,7 @@
     <Compile Include="Arrays.cs" />
     <Compile Include="AssertEx.cs" />
     <Compile Include="Core\Documents\MultipleDocs.cs" />
+    <Compile Include="Core\OutputFormatters\FormatDefault.cs" />
     <Compile Include="Core\Dom\DomContainer.cs" />
     <Compile Include="Core\Dom\InnerText.cs" />
     <Compile Include="Core\Dom\DomText.cs" />

source/CsQuery/Output/OutputFormatterDefault.cs

@@ -430,6 +430,10 @@ protected void RenderCommentNode(IDomObject element, TextWriter writer)
             {
                 return;
             }
+            else if (element.NodeValue.StartsWith("<?") && element.NodeValue.EndsWith("?>"))
+            {
+                writer.Write(element.NodeValue);
+            }
             else
             {
                 writer.Write("<!--" + element.NodeValue + "-->");