URL with javascript: as protocol is valid for various browser operations, java plugin should be able to communicate with browser for that sort of URL. While the API pass to browser usually take string as parameter, there are a couple places in Java plugin code ask for URL type.

However, when try to construct a URL instance with "javascript" as protocol, MalformedURLException could be thrown. See CR 7038890.

Under most circumstances, we should probably use URI class instead of URL as what we need to deal with is a valid URI string, not necessary we want to open the URLConnection.