Handle local functions in kernel_impact.

pkg/compiler/lib/src/js_backend/backend_impact.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.js_helpers.impact;
 
+import '../common/names.dart';
 import '../compiler.dart' show Compiler;
 import '../core_types.dart' show CommonElements;
 import '../dart_types.dart' show InterfaceType;
 import '../elements/elements.dart' show ClassElement, Element;
+import '../universe/selector.dart';
 import 'backend_helpers.dart';
 import 'constant_system_javascript.dart';
 import 'js_backend.dart';
 
 /// A set of JavaScript backend dependencies.
 class BackendImpact {
   final List<Element> staticUses;
+  final List<Selector> dynamicUses;
   final List<InterfaceType> instantiatedTypes;
   final List<ClassElement> instantiatedClasses;
   final List<BackendImpact> otherImpacts;
 
   BackendImpact(
       {this.staticUses: const <Element>[],
+      this.dynamicUses: const <Selector>[],
       this.instantiatedTypes: const <InterfaceType>[],
       this.instantiatedClasses: const <ClassElement>[],
       this.otherImpacts: const <BackendImpact>[]});
 }
 
 /// The JavaScript backend dependencies for various features.
 class BackendImpacts {
   final Compiler compiler;
 
   BackendImpacts(this.compiler);
@@ skipping 318 matching lines @@
           new BackendImpact(staticUses: [helpers.streamIteratorConstructor]);
     }
     return _asyncForIn;
   }
 
   BackendImpact _stringInterpolation;
 
   BackendImpact get stringInterpolation {
     if (_stringInterpolation == null) {
       _stringInterpolation = new BackendImpact(
+          dynamicUses: [Selectors.toString_],
           staticUses: [helpers.stringInterpolationHelper],
           otherImpacts: [_needsString('Strings are created.')]);
     }
     return _stringInterpolation;
   }
 
   BackendImpact _stringJuxtaposition;
 
   BackendImpact get stringJuxtaposition {
     if (_stringJuxtaposition == null) {
@@ skipping 215 matching lines @@
   BackendImpact _closure;
 
   BackendImpact get closure {
     if (_closure == null) {
       _closure = new BackendImpact(
           instantiatedClasses: [commonElements.functionClass]);
     }
     return _closure;
   }
 }