It is not possible to jump to the next or previous editable character if :before or :after CSS rules with generated content are in use.
See the attached files for an example. Place the cursor after ipsum in the first line and press cursor right, or place the cursor before Lorem in the second line and press left. It is not possible to "jump" over the generated content. By pressing Alt (Option) + cursor left/right it is still possible to jump to the previous/next editable word. Using cursor up/down also works.
Created attachment 22426 [details]
Test case XML file
Created attachment 22427 [details]
Test case CSS file
Confirmed as a regression with r35291.