Bug 1058382 - Reorganize |KeyboardManager. inputFocusChange()|

Calling |KeyboardHelper.getLayouts()| doesn't seem to be meaningful here -- the results from getLayouts aren't used at all (i.e KeyboardManager's keyboardLayouts aren't modified by |KM.updateLayouts()|), and the beneficiary effect of it is probably just caching the retrieved apps (there in the KH.getLayouts) -- but since we'll be soon calling activateKeyboard() synchronously, |KH.checkDefaults()| in activeKeyboard will still call updateLayouts.