Fixing jank when transition from print dialog to generating one.

Initially we show the print dialog and when the user presses print
we show a generating dialog with an indefinite spinner and a cancel
button. The transition between the two UIs which are really different
layouts show in the print activity is animated. In the middle of
the animation from print to generating UI there was a jump of the
content and an undesired window animation kicking in. This is a
side effect of changing the activity to floating so now changing the
container size was causing window resize and hence animation. Fun!

bug:10983508

Change-Id: I7d88e073c55863b945cdb50822401592f32d44c3