implement exports, fixes #141

lib/src/js/printer.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.
 
 part of js_ast;
 
 
 class JavaScriptPrintingOptions {
   final bool shouldCompressOutput;
   final bool minifyLocalVariables;
@@ skipping 194 matching lines @@
                             newInForInit: newInForInit,
                             newAtStatementBegin: newAtStatementBegin);
     }
   }
 
   visitAll(List<Node> nodes) {
     nodes.forEach(visit);
   }
 
   visitProgram(Program program) {
+    if (program.scriptTag != null) {
+      out('#!${program.scriptTag}\n');
+    }
     visitAll(program.body);
   }
 
   bool blockBody(Node body, {bool needsSeparation, bool needsNewline}) {
     if (body is Block) {
       spaceOut();
       blockOut(body, false, needsNewline);
       return true;
     }
     if (shouldCompressOutput && needsSeparation) {
@@ skipping 1253 matching lines @@
     declare(node.name);
     node.function.accept(this);
   }
 
   visitClassExpression(ClassExpression node) {
     declare(node.name);
     if (node.heritage != null) node.heritage.accept(this);
     for (Method element in node.methods) element.accept(this);
   }
 }