Resynthesize constructor initializers from Kernel.

pkg/kernel/lib/ast.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.
 
 /// -----------------------------------------------------------------------
 ///                           ERROR HANDLING
 /// -----------------------------------------------------------------------
 ///
 /// As a rule of thumb, errors that can be detected statically are handled by
 /// the frontend, typically by translating the erroneous code into a 'throw' or
@@ skipping 1236 matching lines @@
   Operator,
   Factory,
 }
 
 // ------------------------------------------------------------------------
 //                     CONSTRUCTOR INITIALIZERS
 // ------------------------------------------------------------------------
 
 /// Part of an initializer list in a constructor.
 abstract class Initializer extends TreeNode {
+  /// True if this is a synthetic constructor initializer.
+  @informative
+  bool isSynthetic = false;
+
   accept(InitializerVisitor v);
 }
 
 /// An initializer with a compile-time error.
 ///
 /// Should throw an exception at runtime.
 //
 // DESIGN TODO: The frontend should use this in a lot more cases to catch
 // invalid cases.
 class InvalidInitializer extends Initializer {
@@ skipping 3400 matching lines @@
   if (typedef_.canonicalName == null) {
     throw '$typedef_ has no canonical name';
   }
   return typedef_.canonicalName;
 }
 
 /// Annotation describing information which is not part of Dart semantics; in
 /// other words, if this information (or any information it refers to) changes,
 /// static analysis and runtime behavior of the library are unaffected.
 const informative = null;