Small fixes to top level type inference.

pkg/front_end/lib/src/fasta/kernel/body_builder.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 fasta.body_builder;
 
 import '../fasta_codes.dart'
     show
         FastaMessage,
         codeConstFieldWithoutInitializer,
@@ skipping 420 matching lines @@
       }
       fields.add(field);
       if (initializer != null) {
         if (field.next != null) {
           // TODO(ahe): This can happen, for example, if a final field is
           // combined with a setter.
           internalError(
               "Unhandled: '${field.name}' has more than one declaration.");
         }
         field.initializer = initializer;
-        _typeInferrer.inferFieldInitializer(field.builtType, initializer);
+        _typeInferrer.inferFieldInitializer(
+            field.hasImplicitType ? null : field.builtType, initializer);
       }
     }
     pop(); // Type.
     pop(); // Modifiers.
     List annotations = pop();
     if (annotations != null) {
       Field field = fields.first.target;
       // The first (and often only field) will not get a clone.
       annotations.forEach(field.addAnnotation);
       for (int i = 1; i < fields.length; i++) {
@@ skipping 3234 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }