Add ImportElement and ExportElement

pkg/compiler/lib/src/elements/visitor.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 visitor;
 
 import 'elements.dart';
 import '../closure.dart'
     show BoxFieldElement,
          ClosureClassElement,
          ClosureFieldElement;
 
 abstract class ElementVisitor<R, A> {
   const ElementVisitor();
 
   R visit(Element e, A arg) => e.accept(this, arg);
 
   R visitErroneousElement(ErroneousElement e, A arg) => null;
   R visitWarnOnUseElement(WarnOnUseElement e, A arg) => null;
   R visitAmbiguousElement(AmbiguousElement e, A arg) => null;
   R visitCompilationUnitElement(CompilationUnitElement e, A arg) => null;
   R visitLibraryElement(LibraryElement e, A arg) => null;
+  R visitImportElement(ImportElement e, A arg) => null;
+  R visitExportElement(ExportElement e, A arg) => null;
   R visitPrefixElement(PrefixElement e, A arg) => null;
   R visitTypedefElement(TypedefElement e, A arg) => null;
   R visitVariableElement(VariableElement e, A arg) => null;
   R visitParameterElement(ParameterElement e, A arg) => null;
   R visitFormalElement(FormalElement e, A arg) => null;
   R visitFieldElement(FieldElement e, A arg) => null;
   R visitFieldParameterElement(InitializingFormalElement e, A arg) => null;
   R visitAbstractFieldElement(AbstractFieldElement e, A arg) => null;
   R visitFunctionElement(FunctionElement e, A arg) => null;
   R visitConstructorElement(ConstructorElement e, A arg) => null;
@@ skipping 36 matching lines @@
   R visitCompilationUnitElement(CompilationUnitElement e, A arg) {
     return visitElement(e, arg);
   }
 
   @override
   R visitLibraryElement(LibraryElement e, A arg) {
     return visitScopeContainerElement(e, arg);
   }
 
   @override
+  R visitImportElement(ImportElement e, A arg) {
+    return visitElement(e, arg);
+  }
+
+  @override
+  R visitExportElement(ExportElement e, A arg) {
+    return visitElement(e, arg);
+  }
+
+  @override
   R visitPrefixElement(PrefixElement e, A arg) {
     return visitElement(e, arg);
   }
 
   @override
   R visitTypedefElement(TypedefElement e, A arg) {
     return visitElement(e, arg);
   }
 
   @override
@@ skipping 73 matching lines @@
   @override
   R visitClosureClassElement(ClosureClassElement e, A arg) {
     return visitClassElement(e, arg);
   }
 
   @override
   R visitClosureFieldElement(ClosureFieldElement e, A arg) {
     return visitVariableElement(e, arg);
   }
 }