CB-5193 Fix Android WebSQL sometime throwing SECURITY_ERR.

Turns out our Quota logic has been wrong all along. If we were to
actually track the quota needed, we'd need to store a map of
dbName->quota for all dbNames. Instead, we just set a really high quota
since we don't ever want to decline storage.

I *think* this fixes all of the SECURITY_ERR exceptions we've been
seeing. Even those on Honeycomb / ICS.