Add custom Polymer network icon element

ui/webui/resources/cr_elements/cr_network_icon/cr-network-icon.css

+/*
+ * Copyright 2015 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.
+ */
+
+:host {
+  display: inline-block;
+}
+
+div {
+    border-style: none;
+    height: 100%;
+    margin: 0;
+    overflow: hidden;
+    padding: 0;
+    position: relative;
+    width: 100%;
+}
+
+#icon {
+    height: 100%;
+    position: absolute;
+    width: 100%;
+}
+
+#badge {
+    height: 50%;
+    margin-left: 50%;

[James Hawkins, 2015/02/06 21:37:37]

Let's make sure we've got RTL support from the get-go.

[stevenjb, 2015/02/10 00:22:04]

Generally I agree, but I'm not sure we want to reflect the icon badges in RTL.
We don't in the Chrome status tray.

+    margin-top: 50%;
+    position: absolute;
+    width: 50%;
+}