Switch transformers over to source_span

pkg/third_party/html5lib/lib/src/inputstream.dart

Index: pkg/third_party/html5lib/lib/src/inputstream.dart
diff --git a/pkg/third_party/html5lib/lib/src/inputstream.dart b/pkg/third_party/html5lib/lib/src/inputstream.dart
index 5686abf755598336e8dc4d2898ccdbebc0ff1013..cebe7ad9901908f45c357b05955c5056fe01ade2 100644
--- a/pkg/third_party/html5lib/lib/src/inputstream.dart
+++ b/pkg/third_party/html5lib/lib/src/inputstream.dart
@@ -2,7 +2,7 @@ library inputstream;
 
 import 'dart:collection';
 import 'package:utf/utf.dart';
-import 'package:source_maps/span.dart' show SourceFile;
+import 'package:source_span/source_span.dart';
 import 'char_encodings.dart';
 import 'constants.dart';
 import 'utils.dart';
@@ -135,8 +135,9 @@ class HtmlInputStream {
     // Free decoded characters if they aren't needed anymore.
     if (_rawBytes != null) _rawChars = null;
 
-    fileInfo = new SourceFile(sourceUrl, _lineStarts,
-        generateSpans ? _chars : null);
+    if (generateSpans) {
+      fileInfo = new SourceFile.decoded(_chars, url: sourceUrl);
+    }
   }