ASSERTION FAILED: length.isCalculated() ../../Source/WebCore/css/CSSComputedStyleDeclaration.cpp(502) : WTF::Ref<WebCore::CSSPrimitiveValue> WebCore::valueForImageSliceSide(const WebCore::Length&) This is triggered by the following testcase: https://w3c-test.org/infrastructure/assumptions/html-elements.html more specifically, the tests "CSS div/span definitions (only valid if pre-reqs pass)".
*** Bug 187421 has been marked as a duplicate of this bug. ***
Since it was consistently crashing, I went ahead and skipped this test on debug in https://trac.webkit.org/r233603
Also triggered by https://w3c-test.org/css/css-cascade/all-prop-initial-xml.html: ASSERTION FAILED: length.isCalculated() ./css/CSSComputedStyleDeclaration.cpp(117) : Ref<WebCore::CSSPrimitiveValue> WebCore::valueForImageSliceSide(const WebCore::Length &) 1 0x304adcc59 WTFCrash 2 0x2e80074cb WTFCrashWithInfo(int, char const*, char const*, int) 3 0x2ea5de09c WebCore::valueForImageSliceSide(WebCore::Length const&) 4 0x2ea5c7b52 WebCore::valueForNinePieceImageSlice(WebCore::NinePieceImage const&) 5 0x2ea5ba52a WebCore::ComputedStyleExtractor::valueForPropertyInStyle(WebCore::RenderStyle const&, WebCore::CSSPropertyID, WebCore::RenderElement*) 6 0x2ea5b1cc5 WebCore::ComputedStyleExtractor::propertyValue(WebCore::CSSPropertyID, WebCore::EUpdateLayout) 7 0x2ea5b1a05 WebCore::CSSComputedStyleDeclaration::getPropertyCSSValue(WebCore::CSSPropertyID, WebCore::EUpdateLayout) const 8 0x2ea5cc760 WebCore::CSSComputedStyleDeclaration::getPropertyCSSValueInternal(WebCore::CSSPropertyID) 9 0x2ea6a7c95 WebCore::CSSStyleDeclaration::namedItem(WTF::AtomString const&)
<rdar://problem/64806825>