[MRG] remove QWebView

QWebView provides a widget that wraps QWebPage. But it seems we don't need it because we are not creating a GUI. All tests pass, and I can't find a case where it works different from QWebPage for our use cases.

@andresp99999 - could you please check if it affects your flash rendering branch? 
@pablohoffman - do you recall why have you used QWebView in first place?