Change the type inference for fields in dart2js

lib/compiler/implementation/universe/universe.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('universe');
 
 #import('../closure.dart');
 #import('../elements/elements.dart');
 #import('../leg.dart');
 #import('../scanner/scannerlib.dart');
@@ skipping 458 matching lines @@
   }
 }
 
 class TypedSelector extends Selector {
   /**
    * The type of the receiver. Any subtype of that type can be the
    * target of the invocation.
    */
   final DartType receiverType;
 
-  TypedSelector(this.receiverType, Selector selector)
+  TypedSelector(DartType this.receiverType, Selector selector)
     : super(selector.kind,
             selector.name,
             selector.library,
             selector.argumentCount,
             selector.namedArguments);
 
   /**
    * Check if [element] will be the one used at runtime when being
    * invoked on an instance of [cls].
    */
@@ skipping 35 matching lines @@
 
     if (!self.isInterface() && self.isSubclassOf(other)) {
       // Resolve an invocation of [element.name] on [self]. If it
       // is found, this selector is a candidate.
       return hasElementIn(self, element) && appliesUntyped(element, compiler);
     }
 
     return false;
   }
 }