Small fixes to top level type inference.

pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart

 // Copyright (c) 2017, 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.
 
 /// This file declares a "shadow hierarchy" of concrete classes which extend
 /// the kernel class hierarchy, adding methods and fields needed by the
 /// BodyBuilder.
 ///
 /// Instances of these classes may be created using the factory methods in
 /// `ast_factory.dart`.
@@ skipping 410 matching lines @@
     collector.collectDependencies(then);
     collector.collectDependencies(otherwise);
   }
 
   @override
   DartType _inferExpression(
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
     typeNeeded =
         inferrer.listener.conditionalExpressionEnter(this, typeContext) ||
             typeNeeded;
-    if (!inferrer.isTopLevel) {
+    if (!inferrer.isTopLevel ||
+        TypeInferenceEngineImpl.expandedTopLevelInference) {
       inferrer.inferExpression(
           condition, inferrer.coreTypes.boolClass.rawType, false);
     }
     DartType thenType = inferrer.inferExpression(then, typeContext, true);
     DartType otherwiseType =
         inferrer.inferExpression(otherwise, typeContext, true);
     DartType type = inferrer.typeSchemaEnvironment
         .getLeastUpperBound(thenType, otherwiseType);
     if (inferrer.strongMode) {
       staticType = type;
@@ skipping 1774 matching lines @@
   }
 
   transformChildren(v) {
     return internalError("Internal error: Unsupported operation.");
   }
 
   visitChildren(v) {
     return internalError("Internal error: Unsupported operation.");
   }
 }