Initializes the object for use from C++ code.

Warning: This method must not be called from JavaScript.
[noscript] void init(
  in nsIPrincipal principal,
  in nsIScriptContext scriptContext,
  in nsIGlobalObject globalObject,
  in nsIURI baseURI,
  [optional] in nsILoadGroup loadGroup
The principal to use for the request; this must not be null.
The script context to use for the request; this must not be null.
The object to use as the global for our request. Often, this is the outer Window, but it may also be a sandbox or backstage pass. This may be null, but if it is, the request cannot create a document. Prior to Firefox 23, this was always a Window.
The base URI to use when resolving relative URIs when handling the request. This may be null.
loadGroup Optional
An optional load group used when performing the request. If this is specified, it is used even if the global has a window with a load group already established.