add fasta.scanner support for lazy assignment operators

pkg/analyzer/lib/src/fasta/token_utils.dart

 // Copyright (c) 2016, 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.analyzer.token_utils;
 
 import 'package:front_end/src/fasta/scanner/error_token.dart' show ErrorToken;
 
 import 'package:front_end/src/scanner/token.dart' show Keyword, Token;
 
@@ skipping 303 matching lines @@
             token.lexeme, 0, token.lexeme.length, 0);
       }
       return new CommentToken.fromSubstring(TokenType.SINGLE_LINE_COMMENT,
           token.lexeme, 0, token.lexeme.length, 0);
     case TokenType.STRING:
       return string(TokenType.STRING);
     case TokenType.AMPERSAND:
       return symbol(TokenType.AMPERSAND);
     case TokenType.AMPERSAND_AMPERSAND:
       return symbol(TokenType.AMPERSAND_AMPERSAND);
-    // case TokenType.AMPERSAND_AMPERSAND_EQ
+    case TokenType.AMPERSAND_AMPERSAND_EQ:
+      return symbol(TokenType.AMPERSAND_AMPERSAND_EQ);
     case TokenType.AMPERSAND_EQ:
       return symbol(TokenType.AMPERSAND_EQ);
     case TokenType.AT:
       return symbol(TokenType.AT);
     case TokenType.BANG:
       return symbol(TokenType.BANG);
     case TokenType.BANG_EQ:
       return symbol(TokenType.BANG_EQ);
     case TokenType.BAR:
       return symbol(TokenType.BAR);
     case TokenType.BAR_BAR:
       return symbol(TokenType.BAR_BAR);
-    // case TokenType.BAR_BAR_EQ
+    case TokenType.BAR_BAR_EQ:
+      return symbol(TokenType.BAR_BAR_EQ);
     case TokenType.BAR_EQ:
       return symbol(TokenType.BAR_EQ);
     case TokenType.COLON:
       return symbol(TokenType.COLON);
     case TokenType.COMMA:
       return symbol(TokenType.COMMA);
     case TokenType.CARET:
       return symbol(TokenType.CARET);
     case TokenType.CARET_EQ:
       return symbol(TokenType.CARET_EQ);
@@ skipping 249 matching lines @@
   "hide": analyzer.Keyword.HIDE,
   "native": analyzer.Keyword.NATIVE,
   "of": analyzer.Keyword.OF,
   "on": analyzer.Keyword.ON,
   "patch": analyzer.Keyword.PATCH,
   "show": analyzer.Keyword.SHOW,
   "source": analyzer.Keyword.SOURCE,
   "sync": analyzer.Keyword.SYNC,
   "yield": analyzer.Keyword.YIELD,
 };