VM: [Kernel] Make NativeFieldWrapperClass[1-4] constructible when running from Kernel.

sdk/lib/html/dartium/nativewrappers.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 nativewrappers;
 
-class NativeFieldWrapperClass1 {
-  NativeFieldWrapperClass1() {
-    throw new UnsupportedError(
-        "Generative constructors not supported on native types.");
-  }
-}
+class NativeFieldWrapperClass1 { }
 
-class NativeFieldWrapperClass2 {
-  NativeFieldWrapperClass2() {
-    throw new UnsupportedError(
-        "Generative constructors not supported on native types.");
-  }
-}
+class NativeFieldWrapperClass2 { }
 
-class NativeFieldWrapperClass3 {
-  NativeFieldWrapperClass3() {
-    throw new UnsupportedError(
-        "Generative constructors not supported on native types.");
-  }
-}
+class NativeFieldWrapperClass3 { }
 
-class NativeFieldWrapperClass4 {
-  NativeFieldWrapperClass4() {
-    throw new UnsupportedError(
-        "Generative constructors not supported on native types.");
-  }
-}
-
+class NativeFieldWrapperClass4 { }