Bug 1639747 - Fix context-menu to not detect words at the end of lines.
Bug 1639747 - Fix context-menu to not detect words at the end of lines.

If we're on a text node that ends on a newline, we'd incorrectly move
the start towards the left and keep the end at the newline position.

bill-mccloskey/searchfox,bill-mccloskey/searchfox,bill-mccloskey/searchfox,bill-mccloskey/searchfox,bill-mccloskey/searchfox,bill-mccloskey/searchfox