Yes, it violates the HTML specification.
<!ELEMENT DIV - - (%flow;)* -- generic language/style container -->
(from the div section of the specification)
Follow the hyperlinks in the live version if you want to see exactly how %flow; expands (it doesn't include style).
Browsers just tend to do huge amounts of error recovery because so many authors do stupid things.
Don't depend on error recovery — there are lots of browsers out there, and they don't all behave the same way when the HTML doesn't conform to spec.