Remove mojo/apps/js, it is unused

mojo/apps/js/bindings/monotonic_clock_unittests.js

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-define([
-  "console",
-  "gin/test/expect",
-  "monotonic_clock",
-  "timer",
-  "mojo/apps/js/bindings/threading"
-], function(console, expect, monotonicClock, timer, threading) {
-  var global = this;
-  var then = monotonicClock.seconds();
-  var t = timer.createOneShot(100, function() {
-    var now = monotonicClock.seconds();
-    expect(now).toBeGreaterThan(then);
-    global.result = "PASS";
-    threading.quit();
-  });
-});