Handle deferred access as pre-step in SemanticSendVisitor.

pkg/compiler/lib/src/resolution/resolution_result.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.
 
 part of resolution;
 
 enum ResultKind {
   NONE,
   ELEMENT,
   TYPE,
   ASSERT,
   CONSTANT,
+  PREFIX,
 }
 
 /// The result of resolving a node.
 abstract class ResolutionResult {
   const ResolutionResult();
 
   // TODO(johnniwinther): Remove this factory constructor when `null` is never
   // passed as an element result.
   factory ResolutionResult.forElement(Element element) {
     return element != null ? new ElementResult(element) : const NoneResult();
   }
 
   ResultKind get kind;
   Node get node => null;
   Element get element => null;
   DartType get type => null;
   ConstantExpression get constant => null;
   bool get isConstant => false;
 }
 
+/// The prefix of top level or member access, like `prefix.member`,
+/// `prefix.Class.member` or `Class.member`.
+class PrefixResult extends ResolutionResult {
+  final PrefixElement prefix;
+  final ClassElement cls;
+
+  PrefixResult(this.prefix, this.cls);
+
+  Element get element => cls != null ? cls : prefix;
+
+  bool get isDeferred => prefix != null && prefix.isDeferred;
+
+  ResultKind get kind => ResultKind.PREFIX;
+
+  String toString() => 'PrefixResult($prefix,$cls)';
+}
+
 /// The result for the resolution of a node that points to an [Element].
 class ElementResult extends ResolutionResult {
   final Element element;
 
   ResultKind get kind => ResultKind.ELEMENT;
 
-  ElementResult(this.element);
+  ElementResult(this.element) {
+    assert(element != null);
+  }
 
   String toString() => 'ElementResult($element)';
 }
 
 /// The result for the resolution of a node that points to an [DartType].
 class TypeResult extends ResolutionResult {
   final DartType type;
 
   TypeResult(this.type) {
     assert(type != null);
@@ skipping 60 matching lines @@
 
   /// Returns the list of [ConstantExpression]s for each of the arguments. If
   /// [isValidAsConstant] is `false`, `null` is returned.
   List<ConstantExpression> get constantArguments {
     if (!isValidAsConstant) return null;
     return argumentResults.map((ResolutionResult result) {
       return result.constant;
     }).toList();
   }
 }