Put a TypeProvider on the TypeSystem implementations.

pkg/analysis_server/lib/src/services/refactoring/extract_method.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 services.src.refactoring.extract_method;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/name_suggestion.dart';
@@ skipping 1201 matching lines @@
     if (type.isBottom) {
       return;
     }
     // combine types
     if (returnType == null) {
       returnType = type;
     } else {
       if (returnType is InterfaceType && type is InterfaceType) {
         returnType = InterfaceType.getSmartLeastUpperBound(returnType, type);
       } else {
-        returnType = context.typeSystem
-            .getLeastUpperBound(context.typeProvider, returnType, type);
+        returnType = context.typeSystem.getLeastUpperBound(returnType, type);
       }
     }
   }
 }
 
 /**
  * Generalized version of some source, in which references to the specific
  * variables are replaced with pattern variables, with back mapping from the
  * pattern to the original variable names.
  */
@@ skipping 10 matching lines @@
       return false;
     }
     for (int i = 0; i < parameterTypes.length; i++) {
       if (other.parameterTypes[i] != parameterTypes[i]) {
         return false;
       }
     }
     return true;
   }
 }