dart2js cleanup: remove unused imports and variables

pkg/compiler/lib/src/parser/parser.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 dart2js.parser;
 
 import '../options.dart' show ParserOptions;
 import '../common.dart';
 import '../tokens/keyword.dart' show Keyword;
 import '../tokens/precedence.dart' show PrecedenceInfo;
 import '../tokens/precedence_constants.dart'
     show
         AS_INFO,
         ASSIGNMENT_PRECEDENCE,
         CASCADE_PRECEDENCE,
         EQUALITY_PRECEDENCE,
         GT_INFO,
-        GT_GT_INFO,
         IS_INFO,
         MINUS_MINUS_INFO,
         OPEN_PAREN_INFO,
         OPEN_SQUARE_BRACKET_INFO,
         PERIOD_INFO,
         PLUS_PLUS_INFO,
         POSTFIX_PRECEDENCE,
         QUESTION_INFO,
         QUESTION_PERIOD_INFO,
         RELATIONAL_PRECEDENCE;
@@ skipping 2832 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }