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 609 matching lines @@
 }
 
 // TODO(kasperl): This probably shouldn't be called an element. It's
 // just an interface shared by classes and libraries.
 abstract class ScopeContainerElement implements Element {
   Element localLookup(String elementName);
 
   void forEachLocalMember(f(Element element));
 }
 
+abstract class ClosureContainer implements Element {
+  List<FunctionElement> get nestedClosures;
+}
+
 abstract class CompilationUnitElement extends Element {
   Script get script;
   PartOf get partTag;
 
   void forEachLocalMember(f(Element element));
   void addMember(Element element, DiagnosticListener listener);
   void setPartOf(PartOf tag, DiagnosticListener listener);
   bool get hasMembers;
 
   int compareTo(CompilationUnitElement other);
@@ skipping 85 matching lines @@
 
   bool get isResolved;
 
   // TODO(kasperl): Try to get rid of these setters.
   void set alias(DartType value);
   void set functionSignature(FunctionSignature value);
 
   void checkCyclicReference(Compiler compiler);
 }
 
-abstract class VariableElement extends Element {
+abstract class VariableElement extends Element implements ClosureContainer {
   VariableListElement get variables;
 
   // TODO(kasperl): Try to get rid of this.
   Expression get cachedNode;
 }
 
 abstract class FieldParameterElement extends VariableElement {
   VariableElement get fieldElement;
 }
 
@@ skipping 32 matching lines @@
 
   void forEachParameter(void function(Element parameter));
   void forEachRequiredParameter(void function(Element parameter));
   void forEachOptionalParameter(void function(Element parameter));
 
   void orderedForEachParameter(void function(Element parameter));
 
   bool isCompatibleWith(FunctionSignature constructorSignature);
 }
 
-abstract class FunctionElement extends Element {
+abstract class FunctionElement extends Element implements ClosureContainer {
   FunctionExpression get cachedNode;
   DartType get type;
   FunctionSignature get functionSignature;
   FunctionElement get redirectionTarget;
   FunctionElement get defaultImplementation;
 
   FunctionElement get patch;
   FunctionElement get origin;
 
   bool get isRedirectingFactory;
@@ skipping 184 matching lines @@
   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);
 }
 
 abstract class VoidElement extends Element {}