Ensure layout in getExtendedPadding calls

There are cases in which getExtendedPaddingTop() and Bottom can get
called even without a valid layout. This patch just makes sure there
is some reasonable layout available.

Fix for bug 14819392 "java.lang.NullPointerException in
android.widget.TextView"

Change-Id: I203899402ddfe857a688b16b7855a8991eee82b7