Reduce the amount of SVGElement::updateRelativeLengthsInformation() c…

…alls

https://bugs.webkit.org/show_bug.cgi?id=260971

Reviewed by Ryosuke Niwa.

Reduce the amount of SVGElement::updateRelativeLengthsInformation() calls.

In SVGElement::removedFromAncestor(), if `removalType.disconnectedFromDocument`
was true, we would call `updateRelativeLengthsInformation(false, *this)` to remove
the element from m_elementsWithRelativeLengths and from our ancestor's map.

However, when SVGElement::removedFromAncestor() gets called, we know that
the element either doesn't have a parent or that it's parent is not connected
(I added an assertion to this effect). As a result, recursively calling
`updateRelativeLengthsInformation(false, element)` on the ancestors had no
effect, since the function would early return at the `!isConnected()` check.

As a result, it is sufficient to clear m_elementsWithRelativeLengths in
SVGElement::removedFromAncestor(), without calling
`updateRelativeLengthsInformation(false, *this)` or worrying about the
ancestors.

* Source/WebCore/svg/SVGElement.cpp:
(WebCore::SVGElement::removedFromAncestor):

Canonical link: https://commits.webkit.org/267517@main

Source/WebCore/svg/SVGElement.cpp

@@ -171,8 +171,10 @@ void SVGElement::reportAttributeParsingError(SVGParsingError error, const Qualif
 
 void SVGElement::removedFromAncestor(RemovalType removalType, ContainerNode& oldParentOfRemovedTree)
 {
-    if (removalType.disconnectedFromDocument)
-        updateRelativeLengthsInformation(false, *this);
+    if (removalType.disconnectedFromDocument) {
+        ASSERT(!parentNode() || !parentNode()->isConnected());
+        m_elementsWithRelativeLengths.clear();
+    }
 
     StyledElement::removedFromAncestor(removalType, oldParentOfRemovedTree);