Constrain type annotations with deferred types.

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

 // Copyright (c) 2013, 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.modelx;
 
 import 'elements.dart';
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 998 matching lines @@
   }
 
   accept(ElementVisitor visitor) => visitor.visitLibraryElement(this);
 }
 
 class PrefixElementX extends ElementX implements PrefixElement {
   Token firstPosition;
 
   final ImportScope importScope = new ImportScope();
 
+  bool isDeferred = false;
+
   PrefixElementX(String prefix, Element enclosing, this.firstPosition)
       : super(prefix, ElementKind.PREFIX, enclosing);
 
   Element lookupLocalMember(String memberName) => importScope[memberName];
 
   DartType computeType(Compiler compiler) => compiler.types.dynamicType;
 
   Token position() => firstPosition;
 
   void addImport(Element element, Import import, DiagnosticListener listener) {
     importScope.addImport(this, element, import, listener);
   }
 
   accept(ElementVisitor visitor) => visitor.visitPrefixElement(this);
+
+  void markAsDeferred() {
+    isDeferred = true;
+  }
 }
 
 class TypedefElementX extends ElementX implements TypedefElement {
   Typedef cachedNode;
 
   /**
    * The type of this typedef in which the type arguments are the type
    * variables.
    *
    * This resembles the [ClassElement.thisType] though a typedef has no notion
@@ skipping 1497 matching lines @@
   final Metadata metadata;
 
   ParameterMetadataAnnotation(Metadata this.metadata);
 
   Node parseNode(DiagnosticListener listener) => metadata.expression;
 
   Token get beginToken => metadata.getBeginToken();
 
   Token get endToken => metadata.getEndToken();
 }