Use range-arguments to avoid sublist-iterable and sublists.

pkg/compiler/lib/src/scanner/token.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.
 
 part of scanner;
 
 const int EOF_TOKEN = 0;
 
 const int KEYWORD_TOKEN = $k;
 const int IDENTIFIER_TOKEN = $a;
@@ skipping 367 matching lines @@
     if (!canonicalize) return s;
     var result = canonicalizedSubstrings.lookup(s);
     if (result != null) return result;
     canonicalizedSubstrings.add(s);
     return s;
   }
 
   static String decodeUtf8(List<int> data, int start, int end, bool asciiOnly) {
     var s;
     if (asciiOnly) {
-      // getRange returns an iterator, it does not copy the data.
-      s = new String.fromCharCodes(data.getRange(start, end));
+      s = new String.fromCharCodes(data, start, end);
     } else {
-      // TODO(lry): this is measurably slow. Also sublist is copied eagerly.
-      var bytes = data.sublist(start, end);
-      s = UTF8.decode(bytes);
+      s = UTF8.decoder.convert(data, start, end);
     }
     return canonicalizedString(s, true);
   }
 }
 
 /**
  * This class represents the necessary information to compute a substring
  * lazily. The substring can either originate from a string or from
  * a [:List<int>:] of UTF-8 bytes.
  */
@@ skipping 318 matching lines @@
 
 const PrecedenceInfo STRING_INTERPOLATION_IDENTIFIER_INFO =
   const PrecedenceInfo('\$', 0,
                        STRING_INTERPOLATION_IDENTIFIER_TOKEN);
 
 const PrecedenceInfo HEXADECIMAL_INFO =
   const PrecedenceInfo('hexadecimal', 0, HEXADECIMAL_TOKEN);
 
 const PrecedenceInfo COMMENT_INFO =
   const PrecedenceInfo('comment', 0, COMMENT_TOKEN);