Fix defaultValue in analyzeInPromotedContext

pkg/compiler/lib/src/typechecker.dart

 // Copyright (c) 2012, 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 dart2js.typechecker;
 
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'common.dart';
@@ skipping 520 matching lines @@
 
     for (TypePromotion typePromotion in getShownTypePromotionsFor(right)) {
       typePromotion = typePromotion.copy();
       checkTypePromotion(right, typePromotion);
       showTypePromotion(node, typePromotion);
     }
   }
 
   /// Analyze [node] in the context of the known types shown in [context].
   DartType analyzeInPromotedContext(Node context, Node node,
-      {bool mustHaveType: false}) {
+      {bool mustHaveType: true}) {
     Link<TypePromotion> knownForNode = const Link<TypePromotion>();
     for (TypePromotion typePromotion in getShownTypePromotionsFor(context)) {
       typePromotion = typePromotion.copy();
       checkTypePromotion(node, typePromotion, checkAccesses: true);
       knownForNode = knownForNode.prepend(typePromotion);
       registerKnownTypePromotion(typePromotion);
     }
 
     final DartType type = analyze(node, mustHaveType: mustHaveType);
 
@@ skipping 1474 matching lines @@
 
   visitTypedef(Typedef node) {
     // Do not typecheck [Typedef] nodes.
   }
 
   visitNode(Node node) {
     reporter.internalError(node,
         'Unexpected node ${node.getObjectDescription()} in the type checker.');
   }
 }