Specific $popup filters incorrectly converted to $popunder

[gwarser]

First reported here http://forums.mozillazine.org/viewtopic.php?p=14770533#p14770533 and uBlockOrigin/uAssets#759

Describe the issue

uBlock Origin 1.14.14
SeaMonkey 2.49.1

Steps to reproduce -

1. add this filter

   ||adobe.com^$popup

2. visit http://get.adobe.com/flashplayer/about/

3. in the right sidebar of the page, left-click the link "Games".

Result: Link opens in a new tab, as expected, but the original tab is closed. Logger reports this -

||adobe.com^$popup   --   popunder   http://get.adobe.com/flashplayer/about/

[Hrxn]

Is this SeaMonkey specific?

[gorhill]

Issue is in the core code, it happens with Chromium as well.

[gwarser]

In uBlockOrigin/uAssets#759 @mihp reported:

• Browser/version: Firefox Nightly 58.0a1 (2017-10-12) (64-bit)
• uBlock Origin version: uBlock Origin 1.14.14
• URL http://www.triglav.si/zavarovanja/posamezniki/zavarovanja_na_potovanjih/zdravstveno-zavarovanje-na-potovanjih-v-tujini-z-asistenco/zdravstveno-zavarovanje-na-potovanjih-v-tujini-z-asistenco
• Middle click the red button with text "Sklenite zavarovanje - popust do 20 %" that leads to https://skleni.triglav.si/isklepanje/zdravstveno/
• Filter is ||triglav.si/$popup found in: SVN: Slovenian List

[joey04]

I updated my Pale Moon 27.5 to latest 1.14.15b1 and tested this. The Adobe popup isn't blocked at all, even with *$popup, but it does block popups on other sites.
But in Chrome with 1.14.8 it blocks the Adobe popup.

edit: it won't block popups for external links on the Pale Moon forum either (for example, click the accuweather link on this post). But, again, Chrome blocks this popup.

edit2: installed 1.14.8 in Pale Moon (everything else the same) and now all popups are being blocked, exactly like in Chrome.

So it's a regression.

edit: filed new issue for this