The builder I use in the XPath Parser, IXPathBuilder, is specific to this particular project and you would not find documentation for it in external sources.
XslCompiledTransform in the .Net Framework 2.0+ uses exactly the same, but it is internal interface there and it is not mentioned on MSDN.
(reference to the framework version:
IXPathBuider was introduced to allow XPath Parser to not know and not depend on what you use it for and now you represent results of parser. This makes XPath Parser more reusable. Even internally in Framework it
is used with more than one implementation of the IXPathBuilder.
If you can call WebBrowser component outside of the XPath Parser you would be able to call it from your IXPathBuilder implementation.