Use ASTVisitor as in new AST.

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

Index: compiler/java/com/google/dart/compiler/ast/DartUnaryExpression.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartUnaryExpression.java b/compiler/java/com/google/dart/compiler/ast/DartUnaryExpression.java
index 570ed48cb104fd6694c6d873896b0c9616711d05..3e419a0c27dd64e63ec416efa4b4384af2e18119 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartUnaryExpression.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartUnaryExpression.java
@@ -49,24 +49,12 @@ public class DartUnaryExpression extends DartExpression implements ElementRefere
   }
 
   @Override
-  public void traverse(DartVisitor v, DartContext ctx) {
-    if (v.visit(this, ctx)) {
-      if (operator.isCountOperator()) {
-        arg = becomeParentOf(v.acceptLvalue(getArg()));
-      } else {
-        arg = becomeParentOf(v.accept(getArg()));
-      }
-    }
-    v.endVisit(this, ctx);
-  }
-
-  @Override
-  public void visitChildren(DartPlainVisitor<?> visitor) {
+  public void visitChildren(ASTVisitor<?> visitor) {
     arg.accept(visitor);
   }
 
   @Override
-  public <R> R accept(DartPlainVisitor<R> visitor) {
+  public <R> R accept(ASTVisitor<R> visitor) {
     return visitor.visitUnaryExpression(this);
   }