Fix display bug when dismissing CAB

This fixes a debug in `devel/android` where the CAB does not completely disappear after the user clicks the "Done" or "Delete" buttons. However, it breaks two tests: `BaseballCardListWithDataTest#testOnClickCheckboxStopActionMode()` and `BaseballCardListWithDataTest#testOnClickDoneButton()`. It appears to be a race condition between the test and the main UI thread. The test asserts that the "Add" button is visible before the UI thread has a chance to paint it.