[Webkit-unassigned] [Bug 228125] New: [SVG] Attribute change triggers redundant (and out of order) setNeedsLayout call

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=228125

            Bug ID: 228125
           Summary: [SVG] Attribute change triggers redundant (and out of
                    order) setNeedsLayout call
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: zalan at apple.com
                CC: bfulgham at webkit.org, simon.fraser at apple.com,
                    zalan at apple.com

<svg id=changeThis></svg>
<script>
  document.body.offsetHeight;
  changeThis.setAttribute("width","100px");
</script>

The RenderObject::setNeedsLayout(MarkContainingBlockChain) triggered by the SVGElement::attributeChanged (SVGElement::attributeChanged -> SVGSVGElement::svgAttributeChanged -> RenderSVGResource::markForLayoutAndParentResourceInvalidation()) is incorrect and redundant.
Incorrect in the context of how the dirty bits on the render tree should be populated. It is out of order i.e we have to have all the ancestors resolved first when marking descendant renderers dirty.
Redundant because this attribute change on the SVG element also triggers style invalidation as part of the "presentational hints" flow (which applies to pretty much all the valid SVG attributes see SVGElement::hasPresentationalHintsForAttribute) and this style invalidation path would properly update the associated renderer's dirty bit through the normal RenderTreeUpdater process (as if it was just yet another non-svg style update e.g. <div dir=ltr <-changing it to rtl).

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