View source does not work with qrc URLs

For a page loaded from the Qt Resource System the view source feature produces an empty page. Extension of the qrc url scheme handling is needed to fix this.

For reproducing this try one of these alternatives:

• Load a page from qrc (eg. qrc:/index.html) and click the View Source Page menu entry in the context menu
• Use view source url to load the source of the page stored in qrc (eg. view-source:qrc/index.html)
• Try the attached widget example