About:Blank does not clear page

[traynard]

Environment

Firefox with ABP 3.0

How to reproduce

Ensure ABP is enabled

1. Navigate to any website
2. In address bar, remove current URL and enter "About:blank" and submit

Observed behaviour

The address bar is cleared and user can no longer interact with webpage (other than scrolling) but the page is not cleared or "blank" as expected until tabs are switched.

Expected behaviour

after navigating to about:blank, page should be fully cleared.

NOTE: This works fine when ABP is not installed.

[traynard]

Video example (file was too large to attach): ​https://drive.google.com/a/adblockplus.org/file/d/17Gi0UKmt8hd3_PBV6-bzDQ3Pkof4aQam/view?usp=sharing

[mapx]

error in browser console:

Failed to execute ‘postMessage’ on ‘DOMWindow’: The target origin provided 
(‘https://www.google.it’) does not match the recipient window’s origin (‘null’).

I can reproduce the issue in FF 56 but not in FF 57

[trev]

I can also reproduce in Firefox 56. No error message in my case - this error seems to be caused by the particular website and unrelated. This is some kind of Firefox bug, need to be narrowed down.

[mapx]

firefox bug (courtesy of gorhill ​https://github.com/gorhill/uBlock/issues/1930#issuecomment-342818986):

​https://bugzilla.mozilla.org/show_bug.cgi?id=1415194

[trev]

The only strange thing: gorhill filed that bug for Firefox 58, yet I cannot reproduce it with this Firefox version. But if his analysis is correct, we cannot really avoid hitting this bug.

[mapx]

Yeah, he corrected himself, it's about the same buggy FF 56.

[trev]

Then I wonder why he even bothered reporting the bug. It's not like anybody will bother backporting the fix to Firefox 56. If it's fixed in Firefox 57 then all we need to do is wait a week for Firefox 57 to become the current stable release.

Resolving as "invalid" meaning: not our bug and no way of fixing this on our end.