Parser changes to support new export directive

compiler/java/com/google/dart/compiler/ast/ASTVisitor.java

Index: compiler/java/com/google/dart/compiler/ast/ASTVisitor.java
===================================================================
--- compiler/java/com/google/dart/compiler/ast/ASTVisitor.java	(revision 11954)
+++ compiler/java/com/google/dart/compiler/ast/ASTVisitor.java	(working copy)
@@ -49,6 +49,10 @@
     return visitExpression(node);
   }
 
+  public R visitExportDirective(DartExportDirective node) {
+    return visitDirective(node);
+  }
+
   public R visitExpression(DartExpression node) {
     return visitNode(node);
   }