User.js: Disable IndexedDb + better documentation

[nodiscc]

It was reported that disabling indexedDb no longer causes uBlock to break: https://github.com/ghacksuserjs/ghacks-user.js/issues/80#issuecomment-294178018

OT: The PK readme states "IndexedDB could be used for tracking purposes, but is required for some add-ons to work (notably uBlock), so is left enabled". I have indexeddb off and uBo works perfectly. Any sources/references to this? Or is that some old reference to uBlock before gorhill moved to uBlock Origin?

Yes I have not tested this, it might be from an earlier version. Apparently related to pyllyukko/user.js@ce5ba07 -> http://forums.mozillazine.org/viewtopic.php?p=13842047; pyllyukko/user.js#8. I will open an issue for this, thanks.

We should test whether dom.indexedDB.enabled = false still breaks one of the recommended addons and if it doesn't, set it to false.

More links to CVE/problems related to IndexedDb would also be nice.

[Atavic]

One of the main design goals of IndexedDB is to allow large amounts of data to be stored for offline use.

dom.indexedDB.warningQuota: The disk size in megabytes that one origin can consume before the user is prompted for permission. Defaults to 50

IndexedDB is completely disabled in private browsing mode.

EDIT: Indexed_Database_API info.

https://github.com/ChrisAntaki/disable-indexeddb/issues/1

[pyllyukko]

We should test whether dom.indexedDB.enabled = false still breaks one of the recommended addons and if it doesn't, set it to false.

I'll start testing.

IndexedDB is completely disabled in private browsing mode.

Didn't know that. Thanks!

[publicarray]

FYI there is an extension for that: https://addons.mozilla.org/en-US/firefox/addon/disable-indexeddb/

[pyllyukko]

We'll leave it commented out for now.