-webkit-image-set() should be an alias of image-set()

[Sam Sneddon [:gsnedders]]

Per https://github.com/w3c/csswg-drafts/issues/6285, it was decided to make -webkit-image-set a parse-time alias.

[Radar WebKit Bug Importer]

<rdar://problem/82999675>

[Sam Sneddon [:gsnedders]]

per bug 206909 we did actually briefly do this, but this then got reverted due to Gmail breakage, gonna file a new bug for fixing the underlying issue there and mark this as blocked on that

[Sam Sneddon [:gsnedders]]

The prior Gmail issue no longer seems to trivially reproduce, as empty URLs in image-set no longer cause a broken image icon to be shown.

[Karl Dubost]

Not sure why some of these tests are failing 
http://wpt.live/css/css-images/image-set/image-set-parsing.html

But manually it is working. 

> document.body.style.backgroundImage
< ""
> document.body.style['background-image']
< ""
> document.body.style.backgroundImage = "-webkit-image-set(url('example.png') 1x)"
< "-webkit-image-set(url('example.png') 1x)"
> document.body.style.backgroundImage
< "image-set(url(\"example.png\") 1x)"
> document.body.style['background-image']
< "image-set(url(\"example.png\") 1x)"
> document.body.style.getPropertyValue("background-image")
< "image-set(url(\"example.png\") 1x)"

[Karl Dubost]

Probably necessary for Interop2023.

Note that -webkit-image-set() is already an alias of image-set

[Sam Sneddon [:gsnedders]]

It sorta is and sorta isn't. It still has its own parser: https://github.com/WebKit/WebKit/blob/1e76207c4357149a69994b53bb756f31996c13df/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp#L4666

[Karl Dubost]

Ah thanks for the link, Sam. 
I need to dig into this for understanding the differences.

[Ryan Reno]

I can't reproduce the gmail issue with this simple diff:

diff --git a/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp b/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp
index 173d2397e7c4..5c836404e9ba 100644
--- a/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp
+++ b/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp
@@ -4672,10 +4672,8 @@ RefPtr<CSSValue> consumeImage(CSSParserTokenRange& range, const CSSParserContext
             return consumeGeneratedImage(range, context);
 
         if (allowedImageTypes.contains(AllowedImageType::ImageSet)) {
-            if (functionId == CSSValueImageSet)
+            if (functionId == CSSValueImageSet || functionId == CSSValueWebkitImageSet)
                 return consumeImageSet(range, context, (allowedImageTypes | AllowedImageType::RawStringAsURL) - AllowedImageType::ImageSet);
-            if (functionId == CSSValueWebkitImageSet)
-                return consumeImageSet(range, context, AllowedImageType::URLFunction);
         }
     }

But that diff does progress some of the WPT subtests we are currently failing because we don't implement -webkit-image-set as an alias.

[Ryan Reno]

Pull request: https://github.com/WebKit/WebKit/pull/9718

[Ryan Reno]

Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/38394

[EWS]

Committed 259994@main (5e38273c02f7): <https://commits.webkit.org/259994@main>

Reviewed commits have been landed. Closing PR #9718 and removing active labels.