- Implemented the AxisPhysicsModel class, which encapsulates interpolation and
integration of a 1-dimensional physics model in a frame-rate independent
and stable manner.
- Implemented the AxisPhysicsMSDModel class, which models a generic
1-dimensional Mass-Spring-Damper simulation.
- This physical movement simulation code has been implemented separately from
the existing momentum code in Axis.cpp so that it can be utilized by
both the compositor (AsyncPanZoomController) and main thread
(nsGfxScrollFrame).
