Scanner can include comments in the token stream.

lib/compiler/implementation/scanner/byte_array_scanner.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Scanner that reads from a byte array and creates tokens that points
  * to the same array.
  */
 class ByteArrayScanner extends ArrayBasedScanner<ByteString> {
   final List<int> bytes;
 
-  ByteArrayScanner(List<int> this.bytes) : super();
+  ByteArrayScanner(List<int> this.bytes, [bool includeComments = false])
+    : super(includeComments);
 
   int nextByte() => byteAt(++byteOffset);
 
   int peek() => byteAt(byteOffset + 1);
 
   int byteAt(int index) => bytes[index];
 
   AsciiString asciiString(int start, int offset) {
     return AsciiString.of(bytes, start, byteOffset - start + offset);
   }
 
   Utf8String utf8String(int start, int offset) {
     return Utf8String.of(bytes, start, byteOffset - start + offset + 1);
   }
 
   void appendByteStringToken(PrecedenceInfo info, ByteString value) {
     tail.next = new ByteStringToken(info, value, tokenStart);
     tail = tail.next;
   }
 
   // This method should be equivalent to the one in super. However,
   // this is a *HOT* method and Dart VM performs better if it is easy
   // to inline.
   int advance() => bytes[++byteOffset];
 }