Browser: fix weird behavior in the settings

The summary of the text encoding preference should always be displayed.

Change-Id: I5620cc147bdda078b9350f82b68b3d86774bc09c
Browser: add valid missing fragments (fixes FC)

WebsiteSettingsFragment and DebugPreferencesFragment are also valid
fragments.

Change-Id: I4e945a3b9de62879afcc621fb97811e75ca53cb1