Cascading order for !important properties in ::slotted and ::host rules is incorrect

• Component: CSS
• Status: RESOLVED FIXED

[Antti Koivisto]

https://drafts.csswg.org/css-scoping-1/#shadow-cascading

"When comparing two declarations that have different tree contexts, then for normal rules the declaration earlier in the shadow-including tree order wins, and for important rules the declaration coming later in the shadow-including tree order wins."

[Radar WebKit Bug Importer]

<rdar://problem/26318781>

[Antti Koivisto]

Created attachment 279109 [details]
patch

[Build Bot]

Comment on attachment 279109 [details]
patch

Attachment 279109 [details] did not pass mac-ews (mac):
Output: http://webkit-queues.webkit.org/results/1335960

Number of test failures exceeded the failure limit.

[Build Bot]

Created attachment 279111 [details]
Archive of layout-test-results from ews101 for mac-yosemite

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: ews101  Port: mac-yosemite  Platform: Mac OS X 10.10.5

[Antti Koivisto]

Created attachment 279118 [details]
patch

[Antti Koivisto]

Created attachment 279122 [details]
patch

[Andreas Kling]

Comment on attachment 279122 [details]
patch

r=me

[Ryosuke Niwa]

Comment on attachment 279122 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=279122&action=review

> Source/WebCore/css/StyleResolver.cpp:2414
> +static bool hasImportantProperties(const StyleProperties& properties)
> +{
> +    for (unsigned i = 0, count = properties.propertyCount(); i < count; ++i) {
> +        if (properties.propertyAt(i).isImportant())
> +            return true;
> +    }
> +    return false;
> +}

It seems a bit inefficient to call propertyAt just to find an important property.
Can we add a new helper method on StyleProperty instead?

[Antti Koivisto]

https://trac.webkit.org/r201073