Remove backends.

compiler/java/com/google/dart/compiler/backend/js/ast/JsEmpty.java

Index: compiler/java/com/google/dart/compiler/backend/js/ast/JsEmpty.java
diff --git a/compiler/java/com/google/dart/compiler/backend/js/ast/JsEmpty.java b/compiler/java/com/google/dart/compiler/backend/js/ast/JsEmpty.java
deleted file mode 100644
index c2ac99e3ac06e39fdc9a67d779150d3f3e5d81a1..0000000000000000000000000000000000000000
--- a/compiler/java/com/google/dart/compiler/backend/js/ast/JsEmpty.java
+++ /dev/null
@@ -1,26 +0,0 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// 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;
-
-/**
- * Represents an empty statement in JavaScript.
- */
-public class JsEmpty extends JsStatement {
-
-  // Interned by JsProgram
-  JsEmpty() {
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext ctx) {
-    v.visit(this, ctx);
-    v.endVisit(this, ctx);
-  }
-
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.EMPTY;
-  }
-}