Complain about incorrect this/super constructor initializers.

pkg/front_end/lib/src/fasta/kernel/kernel_builder.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.kernel_builder;
 
 export 'kernel_class_builder.dart' show KernelClassBuilder;
 
 export 'kernel_enum_builder.dart' show KernelEnumBuilder;
 
@@ skipping 30 matching lines @@
 
 export 'kernel_variable_builder.dart' show KernelVariableBuilder;
 
 export 'kernel_invalid_type_builder.dart' show KernelInvalidTypeBuilder;
 
 import 'package:kernel/text/ast_to_text.dart' show Printer;
 
 import 'package:kernel/ast.dart'
     show
         Class,
+        Constructor,
         DartType,
         DynamicType,
         Field,
+        Initializer,
         Library,
         Member,
         Procedure,
+        RedirectingInitializer,
         TypeParameter;
 
 import '../errors.dart' show inputError;
 
 import '../builder/builder.dart' show LibraryBuilder;
 
 List<DartType> computeDefaultTypeArguments(LibraryBuilder library,
     List<TypeParameter> typeParameters, List<DartType> arguments) {
   // TODO(ahe): Not sure what to do if `arguments.length !=
   // cls.typeParameters.length`.
@@ skipping 38 matching lines @@
   }
   name = (cls == null ? "" : "${cls.name}::") + name;
   return inputError(uri, charOffset, "Error in $name: $error");
 }
 
 int compareProcedures(Procedure a, Procedure b) {
   int i = a.fileUri.compareTo(b.fileUri);
   if (i != 0) return i;
   return a.fileOffset.compareTo(b.fileOffset);
 }
+
+bool isRedirectingGenerativeConstructorImplementation(Constructor constructor) {
+  List<Initializer> initializers = constructor.initializers;
+  return initializers.length == 1 &&
+      initializers.single is RedirectingInitializer;
+}