Update scanner so tests pass.

pkg/dart_scanner/lib/src/utf8_bytes_scanner.dart

 // Copyright (c) 2013, 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.
 
-library scanner.utf8_bytes_scanner;
+library dart_scanner.utf8_bytes_scanner;
 
 import 'dart:convert' show
     UNICODE_BOM_CHARACTER_RUNE,
     UTF8;
 
 import 'precedence.dart' show
     PrecedenceInfo;
 
 import 'token.dart' show
     StringToken,
@@ skipping 181 matching lines @@
 
   void appendSubstringToken(PrecedenceInfo info, int start, bool asciiOnly,
       [int extraOffset = 0]) {
     tail.next = new StringToken.fromUtf8Bytes(
         info, bytes, start, byteOffset + extraOffset, asciiOnly, tokenStart);
     tail = tail.next;
   }
 
   bool atEndOfFile() => byteOffset >= bytes.length - 1;
 }