cosmetic filtering causes a layout re-flow during page-load - follow up to #8197

[LaurenWags]

Description

Found while testing #8197

Issue as originally described in above issue is still occurring. If I navigate to articles on latimes.com (with cosmetic blocking enabled), page content jumps around. If I disable cosmetic blocking, page content does not jump around.

Steps to Reproduce

1. Visit latimes.com
2. Visit some articles (with cosmetic blocking enabled by default)

Actual result:

Content jumps (content jumps when cosmetic blocking is on/default)

Expected result:

Content should not jump (it does not jump when cosmetic blocking is disabled)

Reproduces how often:

easily

Brave version (brave://version info)

Brave	1.7.86 Chromium: 80.0.3987.163 (Official Build) (64-bit)
Revision	e7fbe071abe9328cdce4ffedac9822435fbd3656-refs/branch-heads/3987@{#1037}
OS	macOS Version 10.14.6 (Build 18G3020)

Version/Channel Information:

• Can you reproduce this issue with the current release? not on 1.5.x with cosmetic blocking off (default value on this version)
• Can you reproduce this issue with the beta channel? yes
• Can you reproduce this issue with the dev channel? yes
• Can you reproduce this issue with the nightly channel? yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

cc @rebron @brave/legacy_qa

[btlechowski]

Reproduced on Ubuntu

Brave	1.7.86 Chromium: 80.0.3987.163 (Official Build) (64-bit)
Revision	e7fbe071abe9328cdce4ffedac9822435fbd3656-refs/branch-heads/3987@{#1037}
OS	Ubuntu 18.04 LTS

[rebron]

cc: @pes10k @antonok-edm can you take a look?

[pes10k]

In general, this isn't a bug, its a necessary part of the "distinguish 1p vs 3p ads" requirement. We hide everything and then unhide things the algorithm thinks is a 1p ad. Unfortunately, that will cause somethings to jump around as the "party-ness" of it changes.

However, in this specific case, i dont know why the ad would be classified as 1p…

It looks like uBO uses scriptlets to clean up this page. A fix for scriptlets should be incoming shortly (re @antonok-edm). If that doesn't address the problem here, lets re-visit then

[rebron]

@antonok-edm related issue? #9496 or resolved with brave/brave-core#5402?

[antonok-edm]

@rebron Still seeing similar jumping around the advertisement slots using the latest Nightly. I don't think the scriptlets actually touch any of those elements.

[ryanbr]

Looking good here, tested on latimes.com @LaurenWags Feel free to re-open if its still an issue,