Bug 988133 - Workaround crashes in nsDocShellEditorData::ReattachToWindow() when doing view source in a remote tab. r=felipe.

This bug works around the crash by not retrieving the document from the cache, but by
hitting the network again for the document source. That's clearly not ideal, but the
crash is worse. This is a band-aid solution until we can get the cache retrieval
working properly. This workaround should not ride the trains to release.