Take new screen shot before kill previous one.

This issue happened while continues start rotation animation twice.
For the second time startFreezingDisplay, if previous
ScreenRotationAnimation object is animating, in original flow we would
kill previous animation object which would remove the surfaces with a
transaction, then take a new screen shot and apply those new surfaces
with another transaction.
Because the second screen shot is taken after previous animation's
surfaces just been removed, so it may not fluent with original
frame.
To make the animation smooth, take the screen shot before kill
previous screen rotation animation.

Bug: 148192402
Test: Change display or font size in Settings quickly and monitoring
no flicker occurred.

Change-Id: Ie351a68e8b813e888756f9578da3a00c5c1c017f