Small fixes to top level type inference.

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

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 99f2340a4c1b29e52282b052513723bc81333277..2afbb2b6ff9d1bd070dee02c75b111f7ea2eb15f 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -438,7 +438,8 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
               "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.