Check starting data to decide whether to skip IME animation

Since [1], the snapshot will be removed when the transition of
an opening app is finished. That makes the assumption of [2]
no longer true (getTaskSnapshot will be null).

Because the starting window still keeps the info about whether
the snapshot contains IME, it can still achieve original behavior
by checking the starting data.

[1]: I5256fe0f8b6a68a82b269a534d0700c8d5dead09
[2]: I83ffc03119e01da71ad12f8ad8043cf0730dfd50

Bug: 166736352
Bug: 329781040
Test: Launch Chrome, click search bar to show IME.
      Return to home while keep IME on chrome.
      Use gesture navigation to swipe to chrome.
      No additional IME show animation.
Change-Id: Ie2d72834db5e5248f25a375c5894df00c946695c