Workspace: Don't remove icons if dragged to app info drop target

Change-Id: I9bfd0597e7dc88eff97d677aadb7eebc0e442b2c
Trebuchet : Avoid unecessary generatePressedFocusedStates

When the drawable's state changes, don't generate state
drawables until after the invalidate call, which takes care of this
already, otherwise it gets drawn before measure/layout gets a chance to run.

Change-Id: I92543302730446abbb11e3c9c963bd12689cdc7b
Trebuchet : Fix appInfo crash for hotseat

Change-Id: I070f9b3f490b3105a57126180c90aab1b4e7829b