Fix defaultValue in analyzeInPromotedContext

pkg/compiler/lib/src/typechecker.dart

Index: pkg/compiler/lib/src/typechecker.dart
diff --git a/pkg/compiler/lib/src/typechecker.dart b/pkg/compiler/lib/src/typechecker.dart
index 192699d69e67050486ff05619eeb3d0d9bacef96..94a88bb4367d7a421911e66918a67260de739762 100644
--- a/pkg/compiler/lib/src/typechecker.dart
+++ b/pkg/compiler/lib/src/typechecker.dart
@@ -538,7 +538,7 @@ class TypeCheckerVisitor extends Visitor<DartType> {
 
   /// 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();