Fix PunchHole when punching a Rectangle shape

This CL fixes PunchHole in the case where we punch a hole using a
RectangleShape. Before this CL, we would use the size of the element in
which we punch the hole instead of using the size of the `bounds`
element.

Bug: 290184746
Test: Manual, see http://go/sysui-transition-layout#punch-hole
Change-Id: I5d2a0f17e32c2dbaae42ea727e98cff7cec42001