Windows

Quick explanation of the non trivial change: this removes a checksum test and a test for a string which we don't use. This is code that was brought over with ABP. The reason for removing this is that it was preventing the cookie block list from updating. It doesn't seem necessary to me, and since I am trying to rid this code base of ABP anyway I think it's best just to delete it. cc @jsha for review
Pedantic mode: tabId should match case. And official jsdoc style is that the variable name is separated from the description by a space, not a dash. May not matter since I don't think we're planning to extract docs from these in an automated way.