Bug 776547 - Fix spelling in comment DONTBUILD

mobile/android/base/resources/layout/shared_ui_components.xml

@@ -3,8 +3,8 @@
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
-<!-- This file is used to include shared UI components in diffent gecko app
-	 layouts, such as gecko_app.xml and web_app.xml -->
+<!-- This file is used to include shared UI components in different gecko app
+     layouts, such as gecko_app.xml and web_app.xml -->
 
 <merge xmlns:android="http://schemas.android.com/apk/res/android">