Incorporates feedback by Nicolas for UTF-8 bytes based scanner CL

sdk/lib/_internal/compiler/implementation/scanner/utf8_bytes_scanner.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
 part of scanner;
 
 /**
  * Scanner that reads from a UTF-8 encoded list of bytes and creates tokens
  * that points to substrings.
  */
 class Utf8BytesScanner extends ArrayBasedScanner {
   /** The file content. */
   List<int> bytes;
 
   /**
-   * Points to the offset of the byte last returned by [advance].
+   * Points to the offset of the last byte returned by [advance].
    *
    * After invoking [currentAsUnicode], the [byteOffset] points to the last
    * byte that is part of the (unicode or ASCII) character. That way, [advance]
    * can always increase the byte offset by 1.
    */
   int byteOffset = -1;
 
   /**
    * The getter [scanOffset] is expected to return the index where the current
    * character *starts*. In case of a non-ascii character, after invoking
@@ skipping 150 matching lines @@
     if (stringOffsetSlackOffset == byteOffset) {
       return byteOffset - utf8Slack - 1;
     } else {
       return byteOffset - utf8Slack;
     }
   }
 
   Token firstToken() => tokens.next;
   Token previousToken() => tail;
 
-
   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;
   }
 }