Issue 28027. Move Null to the bottom in the Analyzer.

pkg/analyzer/lib/src/task/dart.dart

 // Copyright (c) 2015, 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 analyzer.src.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
@@ skipping 3727 matching lines @@
         visitor.prepareToResolveMembersInClass(
             resolutionContext.enclosingClassDeclaration);
       }
       visitor.initForIncrementalResolution();
       initializer.accept(visitor);
 
       //
       // Record the type of the variable.
       //
       DartType newType = initializer.staticType;
-      if (newType == null || newType.isBottom) {
+      if (newType == null || newType.isBottom || newType.isDartCoreNull) {
         newType = typeProvider.dynamicType;
       }
       setFieldType(variable, newType);
       errors = getUniqueErrors(errorListener.errors);
     } else {
       // TODO(brianwilkerson) For now we simply don't infer any type for
       // variables or fields involved in a cycle. We could try to be smarter
       // by re-resolving the initializer in a context in which the types of all
       // of the variables in the cycle are assumed to be `null`, but it isn't
       // clear to me that this would produce better results often enough to
@@ skipping 2792 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }