Issue 4298 - Enforce 'display: none' for ElemHide

Issue 4298 - Enforce 'display: none' for ElemHide

Based upon the code in these reviews:
https://codereview.adblockplus.org/29347034/
https://codereview.adblockplus.org/29348917/

[kzar, 2016-08-04 15:24:50]

Patch Set 1

[Sebastian Noack, 2016-08-04 20:44:23]

https://codereview.adblockplus.org/29349024/diff/29349025/include.preload.js
File include.preload.js (right):

https://codereview.adblockplus.org/29349024/diff/29349025/include.preload.js#...
include.preload.js:347: Object.defineProperty(style.sheet, "disabled",
Where did the code go, that addressed deleteRule and removeRule?

https://codereview.adblockplus.org/29349024/diff/29349025/include.preload.js#...
include.preload.js:351: Object.defineProperty(style.sheet.rules[i].style,
"display",
How about overriding style.sheet.rules (and sheet.cssRules) so that it always
returns an empty array? That way we wouldn't have to monkey-patch every single
rule which might cause performance issues.

[kzar, 2016-08-05 11:01:57]

Patch Set 2 : Block access to rules instead of attempting to enforce rule styles

https://codereview.adblockplus.org/29349024/diff/29349025/include.preload.js
File include.preload.js (right):

https://codereview.adblockplus.org/29349024/diff/29349025/include.preload.js#...
include.preload.js:347: Object.defineProperty(style.sheet, "disabled",
On 2016/08/04 20:44:23, Sebastian Noack wrote:
> Where did the code go, that addressed deleteRule and removeRule?

This review is based upon the changes in a couple of other reviews. They're
listed in this review's description. That stuff is somewhere near line 400 here,
you'll have to expand the code to see it. Equally if it's easier these changes
are in GitHub too:
https://github.com/kzar/adblockpluschrome/commits/4298-enforce-display-none

I would be happy to combine this review with the review for 4191 since they're
very similar and things are getting confusing. Any objections?

https://codereview.adblockplus.org/29349024/diff/29349025/include.preload.js#...
include.preload.js:351: Object.defineProperty(style.sheet.rules[i].style,
"display",
On 2016/08/04 20:44:23, Sebastian Noack wrote:
> How about overriding style.sheet.rules (and sheet.cssRules) so that it always
> returns an empty array? That way we wouldn't have to monkey-patch every single
> rule which might cause performance issues.

Cool idea, but I actually had to overwrite the getter on
CSSStyleSheet.prototype. 

(It also turns out my old implementation only happened to work for the website
in question by luck. Setting a rule's style to read only doesn't do anything
apparently, it's still writable!)

[Sebastian Noack, 2016-08-11 13:13:19]

I suppose the changes here got redundant, with the changes for #4191 preventing
access to the shadow DOM.

[kzar, 2016-08-11 13:26:50]

On 2016/08/11 13:13:19, Sebastian Noack wrote:
> I suppose the changes here got redundant, with the changes for #4191
preventing
> access to the shadow DOM.

Correct, closing.