Small fixes to top level type inference.

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

Index: pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
diff --git a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
index f9297c8267d2cdab2ea6cca383ee27f0b2db0316..beb9cfe77812ceec07ff6d6ba4a78570e5dcfdbe 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
@@ -591,7 +591,9 @@ abstract class TypeInferrerImpl extends TypeInferrer {
     }
     // TODO(paulberry): if we are doing top level inference and type arguments
     // were omitted, report an error.
-    if (!isTopLevel || isOverloadedArithmeticOperator) {
+    if (!isTopLevel ||
+        isOverloadedArithmeticOperator ||
+        TypeInferenceEngineImpl.expandedTopLevelInference) {
       int i = 0;
       _forEachArgument(arguments, (name, expression) {
         DartType formalType = name != null