Nope. I havent used any of the books.
GWT lets you write Java code which it translates to JS for you. If you know Java
you should be comfortable with this aspect.
GWT uses many Swing concepts like containers and components and listeners and layouts. If you know Java you should be comfortable with this aspect too. Even if you are not a Swing developer, it is not much difficult to pick up.
Rudimentary knowledge of web applications, how they are structured, role of CSS and basics of HTML should help you get started easily.
Of course, if you are stuck anywhere, you can always post your problem here and we can help figure it out with you.
Best of luck