Adrián Pérez de Castro authored Jun 26, 2018 and Michael Natterer committed Jun 25, 2018

This is the minimum set of changes needed to update help-browser to the
WebKitGTK+ 2 API. Fortunately, the plug-in did not use parts of the old
API which would have been difficult to port (DOM bindings, for example),
and therefore the code translates quite well to the new API. The main
differences are:

- WebKitWebFrame is gone, most of its methods are now in WebKitWebView.
- Searching for text inside Web pages has to be done now through the
  WebKitFindController object.
- Checking whether there is selected text that can be copied now goes
  through WebKitEditorState.
- The WebKitWebView::title-changed signal is no more, the callback is
  connected to notify::title instead.
- The load-started and load-finished pair of signals are now merged
  into WebKitWebView::load-changed.
- There are no methods to zoom a WebKitWebView in and out, instead
  the zoom-level property is set. The updated code ensures that the
  zoom lovel stays inside the [0.1, 10.0] range.
- Page visit history now goes through WebKitBackForwardList.

The updated plug-in was successfully built in tested with WebKitGTK+
version 2.20.3.