Because the manuscript was written in DocBook XML, it was fairly easy to programmatically translate the XML into HTML. For some reason, I do not have a copy of the figure from Appendix B that appears in the book, so I had to recreate it myself. Lacking real diagramming tools at the time, I created the original illustration using Google Docs. It took several rounds with the illustrator at O'Reilly to get it reproduced correctly for my book. Since I was too embarrassed to include the Google Docs version in this "HTML reprint," I redid it using Omnigraffle, which I think we can all agree looks much better.
In some ways, the HTML version is better than the print or ebook versions in that (1) the code samples are syntax highlighted, and (2) it is possible to hyperlink to individual sections. Depending on how this is received, I may make more chunks of the book available in the future. As I mentioned, the script to convert the XML to HTML is already written, though it does contain some one-off fixes that would need to be generalized to make it reusable for the other chapters.
If you want to read the rest of Closure: The Definitive Guide (O'Reilly), you can find it on Amazon and other web sites that sell dead trees.