First end-to-end capability in analyzer2dart.

pkg/analyzer2dart/lib/src/closed_world.dart

 // Copyright (c) 2014, 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 analyzer2dart.closedWorld;
 
 import 'dart:collection';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/element.dart';
 
 /**
  * Container for the elements and AST nodes which have been determined by
  * tree shaking to be reachable by the program being compiled.
  */
 class ClosedWorld {
+  /// Returns the main function of this closed world compilation.
+  final FunctionElement mainFunction;
+
   // TODO(paulberry): is it a problem to hold on to all the AST's for the
   // duration of tree shaking & CPS generation?
 
   /**
    * Methods, toplevel functions, etc. that are reachable.
    */
   Map<ExecutableElement, Declaration> executableElements =
       new HashMap<ExecutableElement, Declaration>();
 
   /**
    * Fields that are reachable.
    */
   Map<FieldElement, VariableDeclaration> fields =
       new HashMap<FieldElement, VariableDeclaration>();
 
   /**
    * Classes that are instantiated from reachable code.
    *
    * TODO(paulberry): Also keep track of classes that are reachable but not
    * instantiated (because they are extended or mixed in)
    */
   Map<ClassElement, ClassDeclaration> instantiatedClasses =
       new HashMap<ClassElement, ClassDeclaration>();
 
-  ClosedWorld();
+  ClosedWorld(this.mainFunction);
 }