Enable cascading submenus for screensizes >= 720dp.
Enable cascading submenus for screensizes >= 720dp.

This reflects a decision we'd agreed upon with UX, and will enable
larger tablets like N9 and Pixel C to get the cascading feature.

Bug: 20127825
Change-Id: If3d54d60bc4ca0c7fff37857bbb12dcc6fb7d79a

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base