Added `will-change` property to `Grid` to work around a Chrome bug(?) that caused the entire grid to be repainted whenever a new row or column was added. This was negatively impacting scrolling performance for Chrome under certain conditions. This change is not expected to impact Firefox, Safari, or IE.

Also trapped scroll events inside of `AutoSizer` so that `sdecima/javascript-detect-element-resize` did not treat them as potential resizes and unnecessarily force a sync DOM layout.
