[webkit-dev] Removing support for CSS regions

[Andreas Kling]

> On 2 Aug 2017, at 09:00, Ryosuke Niwa <rniwa at webkit.org> wrote:
> 
> On Tue, Aug 1, 2017 at 11:40 PM, Andreas Kling <akling at apple.com <mailto:akling at apple.com>> wrote:
>> 
>>> On 2 Aug 2017, at 01:03, Ryosuke Niwa <rniwa at webkit.org> wrote:
>>> 
>>> On Mon, Jul 31, 2017 at 1:49 AM, Andreas Kling <akling at apple.com> wrote:
>>>> Some time has passed, and it seems that adoption of CSS regions on the web is not gonna happen.
>>>> 
>>>> Blink has long since removed their support.
>>>> Firefox never supported it AFAIK.
>>>> (The new) IE has some amount of support behind a prefix, but no plans to unprefix AFAIK.
>>>> 
>>>> I think it’s time we remove the code from WebKit, and relieve ourselves of the maintenance burden.
>>>> This should also open up numerous opportunities for clean-up and optimization.
>>>> 
>>>> If you know of any reason to keep the feature, such as a major website or WebKit client depending on it, do speak up now!
>>> 
>>> Since we've been shipping CSS regions for a while, I think the first
>>> step we should take would be disabling the feature on trunk, and put
>>> that into STP and other ports' releases so that we can easily revert
>>> the change if we find out any Web content to be broken when the
>>> feature is disabled.
>> 
>>> Unless there is evidence of at least one major site or client depending on CSS regions, I don’t agree that such a slow removal process is necessary.
>> 
>> IMO doing that would only further increase the maintenance burden incurred by the feature, since we’d have to add tons of runtime checks throughout the codebase.
> 
> Given my concern is the compatibility, not the maintenance cost, what
> is the evidence that nobody is relying on this feature?

While I am not the all-seeing oracle of unused features, I can tell you a few things right now:

- There are no Mac or iOS clients of CSS regions among Apple’s own apps.
- There are no iBooks using CSS regions.
- I could only find one radar about CSS regions from anyone who’s not an engineer working on implementing CSS regions in WebKit.
- That radar was deemed a real bug, but got punted in 2014 because “we don’t know of any high priority regions client.” :|

kling
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