Issue #1: New position is calculated incorrectly

Steps to reproduce:
1. Open attached project
2. Open scene "Demo"
3. Run it
4. After 4~ bounces, history of bounce heights will start to be printed. Notice that height of the ball changes between 4 and 3.92

Issue #2: If rigidbody2D starts off with velocity, bounce height increases

Steps to reproduce:
1. Open attached project
2. Open scene "Demo"
3. Run it
4. Press button "Restart, pos.y = 4 vel.y=1"
5. Notice that after some bounces, ball increases its bounce height. This increase in height becomes more drastic after 20~ bounces

Reproduced with: 5.1.4f1, 5.2.4f1, 5.3.2p3, 5.4.0b6