ScrollShadow implementation through `box-shadow`.
Disable scrollShadow in `cm.dom.setup`
Revert: ScrollShadow implementation through `box-shadow`. (01d8ae9d622f9f14069b2fe5765c2d6a257d7d76)
Disable scrollShadow for narrow devices.
Revert: Disable scrollShadow for narrow devices. (bb2028aace746e3838cc6e866dd50ed299a62ca3)
Remove `webkit-overflow-scrolling` from ScrollShadow.
Revert: Remove `webkit-overflow-scrolling` from ScrollShadow. (2c06e78d1abfe0641396cf0ee9cd18993409a005)
Merge pull request #1412 from vogdb/issue-1412

ScrollShadow plugin doesn't work on mobile/touch browsers