Fixed close tab NPE

 Bug: 3293676
 This was caused by two problems. The first was the code to determine
 the child draw order could break. This cleans up the logic to hopefully
 be clearer and fixes the problem, it is more robust. The root cause
 though was that you could have two tabs pending being closed due to
 a broken animation. This simply removes the animations completely for
 now, how tab open/close should be animated can be addressed in another CL

Change-Id: I06d993a093621bd086ae89162e332357c0e4d94c
1 file changed