I can't see those in the HTML, whether I'm logged in or not, but I have used googleoff & googleon in HTML comments before - they're used to control which parts of a page can be ignored when using a Google Search Appliance.
So, if Quora use a GSA (or rack of them) to power their site search, they can ensure parts of the page aren't added to the index of the search. This can be helpful if you want to exclude areas that are repeated a lot in the site but are not helpful if you are searching, like navigation or help panels.
(Quick edit) googleoff/googleon are completely ignored by normal Google, AFAIK it's only used for their Appliance products.
So, if Quora use a GSA (or rack of them) to power their site search, they can ensure parts of the page aren't added to the index of the search. This can be helpful if you want to exclude areas that are repeated a lot in the site but are not helpful if you are searching, like navigation or help panels.
(Quick edit) googleoff/googleon are completely ignored by normal Google, AFAIK it's only used for their Appliance products.