dart2js: Fix hints in code base.

pkg/compiler/lib/src/js_backend/codegen/glue.dart

 // Copyright (c) 2014, 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 code_generator_dependencies;
 
 import '../js_backend.dart';
 import '../../dart2jslib.dart';
 import '../../js_emitter/js_emitter.dart';
 import '../../js/js.dart' as js;
 import '../../constants/values.dart';
 import '../../elements/elements.dart';
-import '../../constants/expressions.dart';
 import '../../dart_types.dart' show DartType, TypeVariableType, InterfaceType;
 
 /// Encapsulates the dependencies of the function-compiler to the compiler,
 /// backend and emitter.
 // TODO(sigurdm): Should be refactored when we have a better feeling for the
 // interface.
 class Glue {
   final Compiler _compiler;
 
   CodegenEnqueuer get _enqueuer => _compiler.enqueuer.codegen;
@@ skipping 209 matching lines @@
   }
 
   bool operatorEqHandlesNullArgument(FunctionElement element) {
     return _backend.operatorEqHandlesNullArgument(element);
   }
 
   bool hasStrictSubtype(ClassElement element) {
     return _compiler.world.hasAnyStrictSubtype(element);
   }
 }