[6.0] Fix dark theme issues with spy toggle and spy pane (#13345)#13399

stacey-gammon merged 1 commit intoelastic:6.0elastic/kibana:6.0from

stacey-gammon:6.0/fix/dark-theme-spy-togglestacey-gammon/kibana:6.0/fix/dark-theme-spy-toggleCopy head branch name to clipboard