Optimize surface hierarchy

- Do not reset layer if layer doesn't change. JNI is expensive.
- Only assign child layers once if we have to do multiple passes.
- Fix issue where layouting the starting window caused the surface
to be resized, leading to a blocking SF transaction.

Test: go/wm-smoke
Test: adb logcat -b events | grep 319, inspect transition times.
Fixes: 69632880
Change-Id: I8fffca30591730fae87ed3aeb9df0bdf7d4b55dd