Various constant checks.

pkg/front_end/lib/src/fasta/kernel/fasta_accessors.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.
 
 library fasta.fasta_accessors;
 
 export 'frontend_accessors.dart' show wrapInvalid;
 
 import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart'
     show KernelArguments, KernelMethodInvocation;
@@ skipping 31 matching lines @@
 
 import '../names.dart' show callName;
 
 abstract class BuilderHelper {
   Uri get uri;
 
   TypePromoter get typePromoter;
 
   int get functionNestingLevel;
 
+  bool get constantExpressionRequired;
+
   Constructor lookupConstructor(Name name, {bool isSuper});
 
   Expression toSuperMethodInvocation(MethodInvocation node);
 
   Expression toValue(node);
 
   Member lookupSuperMember(Name name, {bool isSetter: false});
 
   scopeLookup(Scope scope, String name, Token token,
       {bool isQualified: false, PrefixBuilder prefix});
@@ skipping 859 matching lines @@
             new NullLiteral(),
             new KernelMethodInvocation(
                 new VariableGet(variable), name, arguments)
               ..fileOffset = offset,
             const DynamicType()));
   } else {
     return new KernelMethodInvocation(receiver, name, arguments)
       ..fileOffset = offset;
   }
 }