Use equals to compare Rect instead of reference comparison.

For the particular test that caught this issue we try to double click on
the PiP window, but interactions are disabled if there's ongoing
animation.
And since this incorrect comparison triggers a new animation, it would
cause that test to fail 50% of the time, depending on whether the
animation finished before the tapping begins.

Bug: 183746978
Test: atest ExpandPipOnDoubleClickTest

Change-Id: I4e700dfe96359381924ae4e4d5df523b56bfd24e