dart2js cleanup: remove unused imports and variables

pkg/compiler/lib/src/js_backend/namer.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 js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  *
  * Names are generated through three stages:
@@ skipping 328 matching lines @@
   final String methodsWithOptionalArgumentsField =
       r'$methodsWithOptionalArguments';
   final String deferredAction = r'$deferredAction';
 
   final String classDescriptorProperty = r'^';
   final String requiredParameterField = r'$requiredArgCount';
 
   /// The non-minifying namer's [callPrefix] with a dollar after it.
   static const String _callPrefixDollar = r'call$';
 
-  static final jsAst.Name _literalSuper = new StringBackedName("super");
   static final jsAst.Name _literalDollar = new StringBackedName(r'$');
   static final jsAst.Name _literalUnderscore = new StringBackedName('_');
   static final jsAst.Name literalPlus = new StringBackedName('+');
   static final jsAst.Name _literalDynamic = new StringBackedName("dynamic");
 
   jsAst.Name _literalAsyncPrefix;
   jsAst.Name _literalGetterPrefix;
   jsAst.Name _literalSetterPrefix;
   jsAst.Name _literalLazyGetterPrefix;
 
@@ skipping 1683 matching lines @@
   void addSuggestion(String original, String suggestion) {
     assert(!_suggestedNames.containsKey(original));
     _suggestedNames[original] = suggestion;
   }
 
   bool hasSuggestion(String original) => _suggestedNames.containsKey(original);
   bool isSuggestion(String candidate) {
     return _suggestedNames.containsValue(candidate);
   }
 }