Fix focus problems when using optimized fragment transactions.

Bug 33754255

Instead of making Views INVISIBLE immediately after adding them,
Views are set to alpha = 0 (or INVISIBLE pre-11) only after they
have been determined to be postponed.

Test: gradlew connectedCheck in fragments/

Change-Id: I474af8ca19f7544afef28067e8d11749ef3571b4
7 files changed