Constrain type annotations with deferred types.

sdk/lib/_internal/compiler/implementation/elements/elements.dart

 // Copyright (c) 2012, 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 elements;
 
 
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 725 matching lines @@
   bool hasLibraryName();
   String getLibraryName();
   String getLibraryOrScriptName();
 
   int compareTo(LibraryElement other);
 }
 
 abstract class PrefixElement extends Element {
   void addImport(Element element, Import import, DiagnosticListener listener);
   Element lookupLocalMember(String memberName);
+  /// Is true if this prefix belongs to a deferred import.
+  bool get isDeferred;
+  void markAsDeferred();
 }
 
 abstract class TypedefElement extends Element
     implements TypeDeclarationElement {
   TypedefType get thisType;
   TypedefType get rawType;
   DartType get alias;
   FunctionSignature get functionSignature;
   Link<DartType> get typeVariables;
 
@@ skipping 363 matching lines @@
   InterfaceType get declarer;
 
   /// Returns `true` if this member is static.
   bool get isStatic;
 
   /// Returns `true` if this member is a getter or setter implicitly declared
   /// by a field.
   bool get isDeclaredByField;
 }