…tainers

* When the scroll position is updated internally (i.e. the inner
  container is scrolled), it previously updated the internal scroll
  state for both axes, which overwrote the scroll position that was
  passed in from props
* If one axis was controlled externally (e.g. by WindowScroller),
  that axis's scroll position was being overwritten
* This fix stops the internal state of an axis from being modified
  if an external scroll position is supplied for that axis
* Additionally, when the external scroll position is modified
  (props are updated), the scroll direction is now updated, so that
  overscanning works for an axis that is controlled, e.g. by a
  WindowScroller

…it's supported by default

Prevent internal scroll position overwriting scroll position from props

This reverts commit 2a90fbf.

This reverts commit 754cb2a.

…y do pointer events if it's window

This reverts commit 6fd41a0.

…t rendered

…er handles window resize events.

…the behavior regarding controlled/uncontrolled and props and in a way that was not backwards compatible. (See issue #490 for more.)

Previously, given two mounted WindowScrollers with different scrollElements, when either scrollElement was scrolled, both WindowScrollers were updated with { isScrolling: true }.