Update model.dart -> modelx.dart.

tests/compiler/dart2js/unparser2_test.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.
 
 import "../../../sdk/lib/_internal/compiler/implementation/scanner/scannerlib.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/tree/tree.dart";
 
 import "../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart"
     show DiagnosticListener,
          Script;
 
 import "../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart"
     show CompilationUnitElement,
          LibraryElement;
 
-import "../../../sdk/lib/_internal/compiler/implementation/elements/model.dart"
+import "../../../sdk/lib/_internal/compiler/implementation/elements/modelx.dart"
     show CompilationUnitElementX,
          LibraryElementX;
 
 main() {
   testClassDef();
   testClass1Field();
   testClass2Fields();
   testClass1Field1Method();
   testClass1Field2Method();
   testClassDefTypeParam();
@@ skipping 56 matching lines @@
   }
   void internalErrorOnElement(Element element, String message) {
     throw message;
   }
   void internalError(String message,
                      {Node node, Token token, dynamic instruction,
                       Element element}) {
     throw message;
   }
 }