Remove BackendClasses and JavaScriptBackendClasses.

pkg/compiler/lib/src/constants/evaluation.dart

 // Copyright (c) 2015, 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.constants.evaluation;
 
 import '../common.dart';
-import '../common/backend_api.dart' show BackendClasses;
 import '../common_elements.dart' show CommonElements;
 import '../elements/entities.dart';
 import '../elements/types.dart';
 import '../universe/call_structure.dart' show CallStructure;
 import 'constructors.dart';
 import 'expressions.dart';
 
 /// Environment used for evaluating constant expressions.
 abstract class Environment {
-  // TODO(johnniwinther): Replace this with [CommonElements] and maybe
-  // [Backend].
   CommonElements get commonElements;
 
-  BackendClasses get backendClasses;
-
   /// Read environments string passed in using the '-Dname=value' option.
   String readFromEnvironment(String name);
 
   /// Returns the [ConstantExpression] for the value of the constant [local].
   ConstantExpression getLocalConstant(Local local);
 
   /// Returns the [ConstantExpression] for the value of the constant [field].
   ConstantExpression getFieldConstant(FieldEntity field);
 
   /// Returns the [ConstantConstructor] corresponding to the constant
@@ skipping 71 matching lines @@
       if (needsComma) {
         sb.write(',');
       }
       sb.write(value.toStructuredText());
       needsComma = true;
     });
     sb.write(']]');
     return sb.toString();
   }
 }