Dart2js option to dump info about compilation

sdk/lib/_internal/compiler/implementation/elements/elements.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 elements;
 
 
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 12 matching lines @@
                                  Compiler;
 
 import '../dart_types.dart';
 
 import '../scanner/scannerlib.dart' show Token,
                                          isUserDefinableOperator,
                                          isMinusOperator;
 
 import '../ordered_typeset.dart' show OrderedTypeSet;
 
+import 'visitor.dart' show ElementVisitor;
+
 const int STATE_NOT_STARTED = 0;
 const int STATE_STARTED = 1;
 const int STATE_DONE = 2;
 
 class ElementCategory {
   /**
    * Represents things that we don't expect to find when looking in a
    * scope.
    */
   static const int NONE = 0;
@@ skipping 207 matching lines @@
   void setFixedBackendName(String name);
 
   Scope buildScope();
 
   /// If the element is a forwarding constructor, [targetConstructor] holds
   /// the generative constructor that the forwarding constructor points to
   /// (possibly via other forwarding constructors).
   FunctionElement get targetConstructor;
 
   void diagnose(Element context, DiagnosticListener listener);
+
+  accept(ElementVisitor visitor) => visitor.visitElement(this);
 }
 
 class Elements {
   static bool isUnresolved(Element e) {
     return e == null || e.isErroneous();
   }
   static bool isErroneousElement(Element e) => e != null && e.isErroneous();
 
   /// Unwraps [element] reporting any warnings attached to it, if any.
   static Element unwrap(Element element,
@@ skipping 713 matching lines @@
   int get resolutionState;
   Token get beginToken;
   Token get endToken;
 
   // TODO(kasperl): Try to get rid of these.
   void set annotatedElement(Element value);
   void set resolutionState(int value);
 
   MetadataAnnotation ensureResolved(Compiler compiler);
 }