* Fix the styling buttons (e.g. bold, italics) in Chrome 65 - and
  probably older. Stack Overflow suggests Chrome 58.
* @dquilter fixed this originally in 8615985, however this behaviour is
  still broken in Sightsavers' ActiveAdmin.
* There's an issue StackOverflow that seems to match the problem we're
  experiencing, and the accepted answer uses the solution applied by DQ,
  however the comments suggest this is only a partial fix, ref:
 * https://stackoverflow.com/q/43674400/885540
 * https://stackoverflow.com/q/43674400/885540#comment75050875_43732840
* This applies the fix recommended by the comment, and that appears to
  have resolved the issue - though I'll be lying if I claim I know why
  `this.caret.set(node1, 0, node2, 0);` solves it.

Fix the styling buttons in Chrome 65