Use ASTVisitor as in new AST.

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

Index: compiler/java/com/google/dart/compiler/ast/DartLibraryDirective.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartLibraryDirective.java b/compiler/java/com/google/dart/compiler/ast/DartLibraryDirective.java
index 18433d7b9240b6c27ef2c449d05eaea7f40bfba6..03f881cbddc617e206a4ffb2995dd1e78636050f 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartLibraryDirective.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartLibraryDirective.java
@@ -19,20 +19,12 @@ public class DartLibraryDirective extends DartDirective {
   }
 
   @Override
-  public void traverse(DartVisitor v, DartContext ctx) {
-    if (v.visit(this, ctx)) {
-      name = becomeParentOf(v.accept(name));
-    }
-    v.endVisit(this, ctx);
-  }
-
-  @Override
-  public void visitChildren(DartPlainVisitor<?> visitor) {
+  public void visitChildren(ASTVisitor<?> visitor) {
     name.accept(visitor);
   }
 
   @Override
-  public <R> R accept(DartPlainVisitor<R> visitor) {
+  public <R> R accept(ASTVisitor<R> visitor) {
     return visitor.visitLibraryDirective(this);
   }
 }