Make the kernel API for promoted type parameter bounds less error-prone.

pkg/kernel/lib/binary/ast_to_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_to_binary;
 
 import '../ast.dart';
 import '../import_table.dart';
 import 'tag.dart';
 import 'dart:convert';
 import 'dart:typed_data';
@@ skipping 1082 matching lines @@
     writeNode(node.type);
   }
 
   visitTypeParameterType(TypeParameterType node) {
     writeByte(Tag.TypeParameterType);
     writeUInt30(_typeParameterIndexer[node.parameter]);
     List<TypeParameter> typeParameters =
         _typeParameterIndexer.indexList[node.parameter];
     writeUInt30(typeParameters[0].binaryOffset);
     writeUInt30(typeParameters.indexOf(node.parameter));
-    writeOptionalNode(node.bound);
+    writeOptionalNode(node.promotedBound);
   }
 
   visitVectorType(VectorType node) {
     writeByte(Tag.VectorType);
   }
 
   visitTypedefType(TypedefType node) {
     writeByte(Tag.TypedefType);
     writeReference(node.typedefReference);
     writeNodeList(node.typeArguments);
@@ skipping 357 matching lines @@
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     flushedLength += length;
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }