Support user generated custom native JS classes.

pkg/compiler/lib/src/inferrer/type_graph_nodes.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.
 
 part of type_graph_inferrer;
 
 /**
  * Common class for all nodes in the graph. The current nodes are:
  *
  * - Concrete types
@@ skipping 397 matching lines @@
       // Use the type annotation as the type for native elements. We
       // also give up on inferring to make sure this element never
       // goes in the work queue.
       giveUp(inferrer);
       if (element.isField) {
         return inferrer.typeOfNativeBehavior(
             native.NativeBehavior.ofFieldLoad(element, inferrer.compiler)).type;
       } else {
         assert(element.isFunction ||
                element.isGetter ||
-               element.isSetter);
+               element.isSetter ||
+               element.isConstructor);
         TypedElement typedElement = element;
         var elementType = typedElement.type;
         if (elementType.kind != TypeKind.FUNCTION) {
           return safeType(inferrer);
         } else {
           return inferrer.typeOfNativeBehavior(
               native.NativeBehavior.ofMethod(element, inferrer.compiler)).type;
         }
       }
     }
@@ skipping 1174 matching lines @@
   T visitStringLiteralTypeInformation(StringLiteralTypeInformation info);
   T visitBoolLiteralTypeInformation(BoolLiteralTypeInformation info);
   T visitClosureCallSiteTypeInformation(ClosureCallSiteTypeInformation info);
   T visitStaticCallSiteTypeInformation(StaticCallSiteTypeInformation info);
   T visitDynamicCallSiteTypeInformation(DynamicCallSiteTypeInformation info);
   T visitMemberTypeInformation(MemberTypeInformation info);
   T visitParameterTypeInformation(ParameterTypeInformation info);
   T visitClosureTypeInformation(ClosureTypeInformation info);
   T visitAwaitTypeInformation(AwaitTypeInformation info);
 }