ResourceRequest: fix NULL pointer access

Do not set the context when the protocol roster failed to create a
request. This would crash the browser when encountering an unhandled
protocol.
Fix DumpRenderTree build.

 * Export WebFrame in the public API since DumpRenderTree uses it
 * Update DumpRenderTree to match the other ports. Most of the methods
are still stubs.
 * Still crashes when running tests from stdin as the testsuite does.
Running from command-line works.
Remove debug traces.
Fix cookie storage again.

 * The UrlContext is stored at the BWebView level, so it is persisted
accross page changes.
 * The FrameNetworkingContext keeps a pointer to the view member field,
so it's possible to change the context on the fly (this allows
 dynamically enabling/disabling private browsing or changing profiles).
 * Keep a global networking context for cases where the application
don't set one. There is currently no way to archive the default cookie
jar to disk, so if that's needed, the application must provide its own
cookie jar and take care of archiving/unarchiving.
Update package revision.