While Firefox does not include a native ad-blocker like Google's Chrome browser, Mozilla the makers of the Firefox browser, seems to be working on an in-page pop-up blocker.
According to a report by Android Police, developers at Mozilla have been asking users for examples of websites which feature pop-ups in order to try and work on a solution. While select ad-blockers allow users to automatically detect pop-ups and then dismiss them, Mozilla intends to work on a solution that allows Firefox to detect the pop-ups and dismiss them on its own.
As pointed out in the report, most pop-up ads violate the Coalition for Better Ads standards, however, a few of them could be useful to the user. As the feature is being worked upon, it will be interesting to see how the Firefox browser is made to distinguish between useful and non-helpful ads.
Mozilla is yet to provide a timeline as to when we could expect the feature to show up on the Firefox browser but considering that it is still in its planning stage, it could take a while. For users who know about websites with annoying pop-ups, you can head over here and fill out the survey.