JS: converted JsEmpty to kotlin

js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsEmpty.kt

@@ -2,28 +2,20 @@
 // 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.
 
-package com.google.dart.compiler.backend.js.ast;
+package com.google.dart.compiler.backend.js.ast
 
-import org.jetbrains.annotations.NotNull;
+public class JsEmpty : SourceInfoAwareJsNode(), JsStatement {
 
-public class JsEmpty extends SourceInfoAwareJsNode implements JsStatement {
-    JsEmpty() {
+    override fun accept(v: JsVisitor) {
+        v.visitEmpty(this)
     }
 
-    @Override
-    public void accept(JsVisitor v) {
-        v.visitEmpty(this);
+    override fun traverse(v: JsVisitorWithContext, ctx: JsContext) {
+        v.visit(this, ctx)
+        v.endVisit(this, ctx)
     }
 
-    @Override
-    public void traverse(JsVisitorWithContext v, JsContext ctx) {
-        v.visit(this, ctx);
-        v.endVisit(this, ctx);
-    }
-
-    @NotNull
-    @Override
-    public JsEmpty deepCopy() {
-        return this;
+    override fun deepCopy(): JsEmpty {
+        return this
     }
 }