[webextension] Blocked iframes are not collapsed (hidden)

[gymka]

Environment

Firefox 57
Adblock Plus 3.0.1
Windows 10 OR Linux (Debian Buster)

How to reproduce

1. Add the filter ||alio.lt/infoNewAuto1200.html.
2. Browse to ​http://margevicius.lt/adas.html

Observed behaviour

While the iframe is blocked from loading, the element itself is not collapsed (hidden). So it remains on the page, but empty.

Expected behaviour

The iframe element should be hidden as well as its src request blocked.

Notes

• This works as expected on Chrome.
• On both platforms a SUBDOCUMENT request to https://www.alio.lt/infoNewAuto1200.html is reported as being blocked.
• The problem seems to be caused by the fact that Firefox doesn't fire a load event for the blocked iframe where as Chrome does. On Chrome the frame is replaced and ends up with the location chrome-error://chromewebdata/ for which the load event is fired. On Firefox the frame isn't being replaced, the location is considered about:blank and therefore the load event is never fired.

[gymka]

for easier testing, my test page ​http://margevicius.lt/adas.html

[kzar]

Which operating system are you using?

[gymka]

Replying to kzar:

Which operating system are you using?

windows 10

[gymka]

change line ||alio.lt/infoNewNT1200.html. to ||alio.lt/infoNewNTFooter1200.html. it's my error, but i can't modify original post
in original page there is both iframes, in my test page only 1

[kzar]

Done. (I think it was my error, I adjusted the filters when I edited the description earlier!)

[kzar]

Please could you modify your test page so that it has two iframes, one using the // prefix and the other using the https:// prefix? That would make it easier for people to see the problem.

I can reproduce this, according to our devtools pane Adblock Plus blocks the SUBDOCUMENT request of http://www.alio.lt/infoNewNTFooter1200.html (note the http prefix despite the page using https), the iframe element is left empty on the page but not collapsed.

I'll investigate further next week.

[gymka]

when i'm testing in test page looks like problem is not about "" or "https" but with all url's, simply adblock plus 3.0.1 rules works differently then old version. old version blocked iframe and removed whitespace, 3.0.1 version only blocks iframe, but leaves whitespace.
issue is not with "src" protocol. then i tested in real life there was a lot of ads, so i assumed it's protocol fault.

[kzar]

when i'm testing in test page looks like problem is not about "" or "https" but with all url's, simply adblock plus 3.0.1 rules works differently then old version. old version blocked iframe and removed whitespace, 3.0.1 version only blocks iframe, but leaves whitespace.
issue is not with "src" protocol. then i tested in real life there was a lot of ads, so i assumed it's protocol fault.

Aha, we're getting somewhere now, I've updated the issue again. Please could you update the test page so that there's only one iframe with the src of https://www.alio.lt/infoNewAuto1200.html ?

I'm going to start investigating what's going on today.

[kzar]

I've filed a bug report with Mozilla about this: ​https://bugzilla.mozilla.org/show_bug.cgi?id=1418975

[Lain_13]

Add me and dimisa into CC here please. Actually, is there a way to add myself into CC on issues without a request?