Handle const Symbol(...) in closed_world2_test

pkg/compiler/lib/src/ssa/kernel_impact.dart

 // Copyright (c) 2016, 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.
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/names.dart';
 import '../compiler.dart';
 import '../constants/expressions.dart';
@@ skipping 252 matching lines @@
 
   @override
   void visitConstructorInvocation(ir.ConstructorInvocation node) {
     handleNew(node, node.target, isConst: node.isConst);
   }
 
   void handleNew(ir.InvocationExpression node, ir.Member target,
       {bool isConst: false}) {
     _visitArguments(node.arguments);
     ConstructorEntity constructor = elementAdapter.getConstructor(target);
+    if (commonElements.isSymbolConstructor(constructor)) {
+      impactBuilder.registerFeature(Feature.SYMBOL_CONSTRUCTOR);
+    }
     InterfaceType type = elementAdapter.createInterfaceType(
         target.enclosingClass, node.arguments.types);
     CallStructure callStructure =
         elementAdapter.getCallStructure(node.arguments);
     impactBuilder.registerStaticUse(isConst
         ? new StaticUse.constConstructorInvoke(constructor, callStructure, type)
         : new StaticUse.typedConstructorInvoke(
             constructor, callStructure, type));
     if (type.typeArguments.any((DartType type) => !type.isDynamic)) {
       impactBuilder.registerFeature(Feature.TYPE_VARIABLE_BOUNDS_CHECK);
@@ skipping 310 matching lines @@
     ConstructorEntity target = elementAdapter.getConstructor(node.target);
     impactBuilder.registerStaticUse(new StaticUse.superConstructorInvoke(
         target, elementAdapter.getCallStructure(node.arguments)));
   }
 
   // TODO(johnniwinther): Make this throw and visit child nodes explicitly
   // instead to ensure that we don't visit unwanted parts of the ir.
   @override
   void defaultNode(ir.Node node) => node.visitChildren(this);
 }