Provides a nicer experience on pages with large trees so that the window
isn't just a large blank screen while it is loading. Instead, send the
trees to the Inspector WebView once they have arrived and have been
transformed to HTML.
We Base64 encode the HTML to avoid needing to deal with all kinds of
nested quotes that may appear in the HTML. We could instead send the
JSON to the WebView, but generating the HTML in C++ feels a bit easier
for now.
353642168a