[WebUI] Fix rest of CSS style nits so I can turn on CSS checker.

chrome/browser/resources/tracing/overlay.css

-/*
-Copyright (c) 2011 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.
-*/
+/* Copyright (c) 2012 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.
+ */
+
 .overlay-root {
+  -webkit-box-align: stretch;
+  -webkit-box-orient: horizontal;
+  -webkit-box-pack: center;
+  -webkit-user-select: none;
+  background: rgba(0, 0, 0, 0.8);
   display: -webkit-box;
+  height: 100%;
+  left: 0;
   position: fixed;
+  top: 0;
   width: 100%;
-  height: 100%;
-  top: 0;
-  left: 0;
-  background: rgba(0, 0, 0, 0.8);
-  -webkit-user-select: none;
-  -webkit-box-orient: horizontal;
-  -webkit-box-align: stretch;
-  -webkit-box-pack: center;
   z-index: 1000;
 }
 
 .overlay-root:not([visible]),
-.overlay:not([visible])
-{
+.overlay:not([visible]) {
   display: none;
 }
 
 .overlay-root > .content-host {
+  -webkit-box-align: stretch;
+  -webkit-box-orient: vertical;
+  -webkit-box-pack: center;
   -webkit-user-select: auto;
   display: -webkit-box;
-  -webkit-box-orient: vertical;
-  -webkit-box-align: stretch;
-  -webkit-box-pack: center;
 }
 
 .overlay-root > .content-host > * {
   background: rgb(255, 255, 255);
 }