Issue 21842. Fix for incremental resolution of function expressions in top-level variables.

pkg/analyzer/lib/src/generated/incremental_resolver.dart

 // Copyright (c) 2014, 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 engine.incremental_resolver;
 
 import 'dart:collection';
 import 'dart:math' as math;
 
 import 'ast.dart';
@@ skipping 375 matching lines @@
   visitVariableDeclaration(VariableDeclaration node) {
     // prepare variable
     String name = node.name.name;
     PropertyInducingElement element;
     if (_inTopLevelVariableDeclaration) {
       element = _findElement(_enclosingUnit.topLevelVariables, name);
     } else {
       element = _findElement(_enclosingClass.fields, name);
     }
     // verify
+    PropertyInducingElement newElement = node.name.staticElement;
     _assertNotNull(element);
     _processElement(element);
     _assertEquals(node.isConst, element.isConst);
     _assertEquals(node.isFinal, element.isFinal);
     if (_enclosingFieldNode != null) {
       _assertEquals(_enclosingFieldNode.isStatic, element.isStatic);
     }
     _assertSameType(
         (node.parent as VariableDeclarationList).type,
         element.type);
     // matches, restore the existing element
     node.name.staticElement = element;
+    if (element is VariableElementImpl) {
+      (element as VariableElementImpl).initializer = newElement.initializer;
+    }
   }
 
   @override
   visitWithClause(WithClause node) {
     List<TypeName> nodes = node.mixinTypes;
     List<InterfaceType> types = _enclosingClass.mixins;
     _assertSameTypes(nodes, types);
   }
 
   void _assertCombinators(List<Combinator> nodeCombinators,
@@ skipping 486 matching lines @@
    *
    * [node] - the node being tested.
    */
   bool _canBeResolved(AstNode node) =>
       node is ClassDeclaration ||
           node is ClassTypeAlias ||
           node is CompilationUnit ||
           node is ConstructorDeclaration ||
           node is FunctionDeclaration ||
           node is FunctionTypeAlias ||
-          node is MethodDeclaration;
+          node is MethodDeclaration ||
+          node is TopLevelVariableDeclaration;
 
   void _fillResolutionQueue(DeclarationMatcher matcher) {
     HashSet<Element> removedElements = matcher._removedElements;
     logger.log('${removedElements.length} elements removed');
     for (Element removedElement in removedElements) {
       AnalysisContextImpl context = removedElement.context;
       IntSet users = removedElement.users;
       while (!users.isEmpty) {
         int id = users.remove();
         Element removedElementUser = context.findElementById(id);
@@ skipping 877 matching lines @@
   String toString() => name;
 }
 
 
 class _TokenPair {
   final _TokenDifferenceKind kind;
   final Token oldToken;
   final Token newToken;
   _TokenPair(this.kind, this.oldToken, this.newToken);
 }