Compute surface position of scaled child window

This replaces the way commit df46fd52 did. The frames of child
window are still calculated with scaling, but only the surface
scale is ignored. So if the app calls getLocationOnScreen for
a scaled child window, the coordinate base can be consistent
with parent.

Bug: 182362657
Test: atest WindowStateTests#testCompatOverrideScale

Change-Id: I6d4f7dab4949feb488fbcb42ff687a520fe4ca70