Switch transformers over to source_span

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

 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';
 import 'encoding_parser.dart';
 
 /// Hooks to call into dart:io without directly referencing it.
 class ConsoleSupport {
   List<int> bytesFromFile(source) => null;
 }
 
@@ skipping 112 matching lines @@
         c = NEWLINE;
       }
 
       _chars.add(c);
       if (c == NEWLINE) _lineStarts.add(_chars.length);
     }
 
     // Free decoded characters if they aren't needed anymore.
     if (_rawBytes != null) _rawChars = null;
 
-    fileInfo = new SourceFile(sourceUrl, _lineStarts,
-        generateSpans ? _chars : null);
+    // TODO(sigmund): Don't parse the file at all if spans aren't being
+    // generated.
+    fileInfo = new SourceFile.decoded(_chars, url: sourceUrl);
   }
 
 
   void detectEncoding([bool parseMeta = true]) {
     // First look for a BOM
     // This will also read past the BOM if present
     charEncodingName = detectBOM();
     charEncodingCertain = true;
 
     // If there is no BOM need to look for meta elements with encoding
@@ skipping 135 matching lines @@
 /// Return the python codec name corresponding to an encoding or null if the
 /// string doesn't correspond to a valid encoding.
 String codecName(String encoding) {
   final asciiPunctuation = new RegExp(
       "[\u0009-\u000D\u0020-\u002F\u003A-\u0040\u005B-\u0060\u007B-\u007E]");
 
   if (encoding == null) return null;
   var canonicalName = encoding.replaceAll(asciiPunctuation, '').toLowerCase();
   return encodings[canonicalName];
 }