Bug 298817 – Fix static_assert() in WebCore::SVGPropertyOwnerRegistry::fastAnimatedPropertyLookup() with upstream clang

• Component: SVG
• Status: RESOLVED FIXED

[David Kilzer (:ddkilzer)]

Fix static_assert() in WebCore::SVGPropertyOwnerRegistry::fastAnimatedPropertyLookup() with upstream clang.

Upstream clang fails to build WebCore with the following error:

```
    Source/WebCore/svg/properties/SVGPropertyOwnerRegistry.h:267:27: error: static assertion failed due to requirement '!std::is_same_v<WebCore::SVGRectElement, WebCore::SVGRectElement>': Element should use fast property path
      267 |             static_assert(!std::is_same_v<OwnerType, SVGRectElement> && !std::is_same_v<OwnerType, SVGCircleElement>, "Element should use fast property path");
          |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Source/WebCore/svg/properties/SVGPropertyOwnerRegistry.h:243:30: note: in instantiation of member function 'WebCore::SVGPropertyOwnerRegistry<WebCore::SVGRectElement, WebCore::SVGGeometryElement>::fastAnimatedPropertyLookup' requested here
      243 |         if (auto* property = fastAnimatedPropertyLookup(m_owner, attributeName)) {
          |                              ^
```

<rdar://157029024>

[David Kilzer (:ddkilzer)]

As I understand it, the issue is that the `propertyForAttribute()` method on `SVGRectElement` is declared `private`, but concept evaluation occurs during template instantiation, before `friend` relationships are considered.

```
template<typename T>
concept HasFastPropertyForAttribute = requires(const T& element, const QualifiedName& name)
{
    { element.propertyForAttribute(name) } -> std::same_as<SVGAnimatedProperty*>;
};
```

Note that the `SVGCircleElement` class has the same issue.

[David Kilzer (:ddkilzer)]

Pull request: https://github.com/WebKit/WebKit/pull/50705

[EWS]

Committed 299969@main (4397d9f07bfd): <https://commits.webkit.org/299969@main>

Reviewed commits have been landed. Closing PR #50705 and removing active labels.