Use ASTVisitor as in new AST.

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

Index: compiler/java/com/google/dart/compiler/ast/DartStringLiteral.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartStringLiteral.java b/compiler/java/com/google/dart/compiler/ast/DartStringLiteral.java
index 5f5891973d7586390e416aa18eb1dd084a252e14..9d7ee82f7864949a29365e3b72df5096b6e24c55 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartStringLiteral.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartStringLiteral.java
@@ -24,17 +24,11 @@ public class DartStringLiteral extends DartLiteral {
   }
 
   @Override
-  public void traverse(DartVisitor v, DartContext ctx) {
-    v.visit(this, ctx);
-    v.endVisit(this, ctx);
+  public void visitChildren(ASTVisitor<?> visitor) {
   }
 
   @Override
-  public void visitChildren(DartPlainVisitor<?> visitor) {
-  }
-
-  @Override
-  public <R> R accept(DartPlainVisitor<R> visitor) {
+  public <R> R accept(ASTVisitor<R> visitor) {
     return visitor.visitStringLiteral(this);
   }
 }