Update tests to check that we can keep the same functionality by
querying document.baseURI through runJavaScript instead of implementing
QWebEnginePage::baseUrl.

This also removes QWebEnginePage::baseUrl from the header.

Change-Id: I549e57d3986e22986438f8a23e469bbd220633b7
Reviewed-by: Pierre Rossi <pierre.rossi@gmail.com>