Resynthesize constructor initializers from Kernel.

pkg/kernel/lib/binary/ast_from_binary.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 kernel.ast_from_binary;
 
 import 'dart:convert';
 import 'dart:typed_data';
 
 import '../ast.dart';
 import '../transformations/flags.dart';
@@ skipping 608 matching lines @@
       node.annotations = annotations;
       node.function = function;
       node.function?.parent = node;
       node.transformerFlags = transformerFlags;
     }
     return node;
   }
 
   Initializer readInitializer() {
     int tag = readByte();
+    bool isSynthetic = readByte() == 1;
     switch (tag) {
       case Tag.InvalidInitializer:
         return new InvalidInitializer();
       case Tag.FieldInitializer:
-        return new FieldInitializer.byReference(
-            readMemberReference(), readExpression());
+        var reference = readMemberReference();
+        var value = readExpression();
+        return new FieldInitializer.byReference(reference, value)
+          ..isSynthetic = isSynthetic;
       case Tag.SuperInitializer:
-        return new SuperInitializer.byReference(
-            readMemberReference(), readArguments());
+        var reference = readMemberReference();
+        var arguments = readArguments();
+        return new SuperInitializer.byReference(reference, arguments)
+          ..isSynthetic = isSynthetic;
       case Tag.RedirectingInitializer:
         return new RedirectingInitializer.byReference(
             readMemberReference(), readArguments());
       case Tag.LocalInitializer:
         return new LocalInitializer(readAndPushVariableDeclaration());
       default:
         throw fail('Invalid initializer tag: $tag');
     }
   }
 
@@ skipping 594 matching lines @@
       ..fileOffset = offset
       ..fileEqualsOffset = fileEqualsOffset;
   }
 
   int readOffset() {
     // Offset is saved as unsigned,
     // but actually ranges from -1 and up (thus the -1)
     return readUInt() - 1;
   }
 }