merge fasta.Token into analyzer.Token

pkg/front_end/lib/src/fasta/scanner/abstract_scanner.dart

 // Copyright (c) 2012, 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 fasta.scanner.abstract_scanner;
 
 import 'dart:collection' show ListMixin;
 
 import 'dart:typed_data' show Uint16List, Uint32List;
 
-import '../../scanner/token.dart' show TokenType;
+import '../../scanner/token.dart' show Token, TokenType;
 
 import '../scanner.dart'
     show ErrorToken, Keyword, Scanner, buildUnexpectedCharacterToken;
 
 import 'error_token.dart' show UnterminatedToken;
 
 import 'keyword_state.dart' show KeywordState;
 
 import 'token.dart'
-    show BeginGroupToken, CommentToken, DartDocToken, SymbolToken, Token;
+    show BeginGroupToken, CommentToken, DartDocToken, SymbolToken;
 
 import 'token_constants.dart';
 
 import 'characters.dart';
 
 abstract class AbstractScanner implements Scanner {
   final bool includeComments;
 
   /**
    * A flag indicating whether to parse generic method comments, of the form
@@ skipping 831 matching lines @@
   }
 
   /**
    * Append the given token to the [tail] of the current stream of tokens.
    */
   void appendToken(Token token) {
     tail.next = token;
     tail.next.previous = tail;
     tail = tail.next;
     if (comments != null) {
-      for (CommentToken c = comments; c != null; c = c.next) {
-        c.parent = tail;
-      }
-      tail.precedingComments = comments;
+      // It is the responsibility of the caller to construct the token
+      // being appended with preceeding comments if any
+      assert(identical(token.precedingComments, comments));
       comments = null;
       commentsTail = null;
     }
   }
 
   void _appendToCommentStream(Token newComment) {
     if (comments == null) {
       comments = newComment;
       commentsTail = comments;
     } else {
@@ skipping 402 matching lines @@
       switchToUint32(newLength);
     }
   }
 
   void switchToUint32(int newLength) {
     final newArray = new Uint32List(newLength);
     newArray.setRange(0, arrayLength, array);
     array = newArray;
   }
 }