Fix Linux keyboard shortcuts
Fix Linux keyboard shortcuts

Summary: Removing the concept of "isWindows", as that seemed to land Linux into a forgotten bucket.  IMO the shortcuts should simply be split between Mac and PC.

Reviewed By: sophiebits

Differential Revision: D6777189

fbshipit-source-id: 9c596c4c544298f0ac46470988ed2992698e0dca

facebook/draft-js