Fix line tracking when printing single-line comments.

ICSharpCode.Decompiler/CSharp/OutputVisitor/TextWriterOutputFormatter.cs

@@ -128,7 +128,8 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 				case CommentType.SingleLine:
 					textWriter.Write("//");
 					textWriter.WriteLine(content);
-					column += 2 + content.Length;
+					column = 1;
+					line++;
 					needsIndent = true;
 					isAtStartOfLine = true;
 					break;
@@ -144,7 +145,8 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 				case CommentType.Documentation:
 					textWriter.Write("///");
 					textWriter.WriteLine(content);
-					column += 3 + content.Length;
+					column = 1;
+					line++;
 					needsIndent = true;
 					isAtStartOfLine = true;
 					break;

ILSpy/Languages/CSharpILMixedLanguage.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Threading;
@@ -116,6 +117,14 @@ namespace ICSharpCode.ILSpy
 
 			void WriteHighlightedCommentLine(ISmartTextOutput output, string text, int startColumn, int endColumn, bool isSingleLine)
 			{
+				if (startColumn > text.Length) {
+					Debug.Fail("startColumn is invalid");
+					startColumn = text.Length;
+				}
+				if (endColumn > text.Length) {
+					Debug.Fail("endColumn is invalid");
+					endColumn = text.Length;
+				}
 				output.Write("// ");
 				output.BeginSpan(gray);
 				if (isSingleLine)