* A PageView is a view onto a Page object.
* A Page always has a main Frame (root of Frame tree.)
* Page has a PageClient. PageView is a PageClient.
The goal here is to allow building another kind of view onto
a Page while keeping the rest of LibWeb intact.
The spec defines the only valid methods to be get, post, and dialog.
Post and dialog are currently unhandled and do nothing, any other value
(or no value specified) is defined by the spec to use the get method.
