fix #27088, future then upwards inference

pkg/analyzer/test/generated/analysis_context_factory.dart

 // Copyright (c) 2016, 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.test.generated.analysis_context_factory;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 194 matching lines @@
         ElementFactory.positionalParameter2("value", provider.dynamicType)
       ];
       futureConstructor.factory = true;
       futureElement.constructors = <ConstructorElement>[futureConstructor];
       //   Future then(onValue(T value), { Function onError });
       TypeDefiningElement futureThenR = DynamicElementImpl.instance;
       if (context.analysisOptions.strongMode) {
         futureThenR = ElementFactory.typeParameterWithType('R');
       }
       FunctionElementImpl thenOnValue = ElementFactory.functionElement3(
-          'onValue', futureThenR, [futureElement.typeParameters[0]], null);
+          'onValue',
+          DynamicElementImpl.instance,
+          [futureElement.typeParameters[0]],
+          null);
       thenOnValue.synthetic = true;
 
       DartType futureRType = futureElement.type.instantiate([futureThenR.type]);
       MethodElementImpl thenMethod = ElementFactory
           .methodElementWithParameters(futureElement, "then", futureRType, [
         ElementFactory.requiredParameter2("onValue", thenOnValue.type),
         ElementFactory.namedParameter2("onError", provider.functionType)
       ]);
       if (!futureThenR.type.isDynamic) {
         thenMethod.typeParameters = [futureThenR];
@@ skipping 354 matching lines @@
 
   void _addLibrary(LibraryMap map, String uri, bool isInternal, String path) {
     SdkLibraryImpl library = new SdkLibraryImpl(uri);
     if (isInternal) {
       library.category = "Internal";
     }
     library.path = path;
     map.setLibrary(uri, library);
   }
 }