BackgroundImage incorrectly returns empty url() when created on-the-fly

Source/core/style/StyleFetchedImageSet.cpp

Index: Source/core/style/StyleFetchedImageSet.cpp
diff --git a/Source/core/style/StyleFetchedImageSet.cpp b/Source/core/style/StyleFetchedImageSet.cpp
index b5732d8fda2289ea1e6afcfeb79089396fd710c4..8c766212726921eaf1176009046f8f3c4b4e3319 100644
--- a/Source/core/style/StyleFetchedImageSet.cpp
+++ b/Source/core/style/StyleFetchedImageSet.cpp
@@ -52,6 +52,11 @@ PassRefPtrWillBeRawPtr<CSSValue> StyleFetchedImageSet::cssValue() const
     return m_imageSetValue;
 }
 
+PassRefPtrWillBeRawPtr<CSSValue> StyleFetchedImageSet::computedCSSValue() const
+{
+    return m_imageSetValue->valueWithURLsMadeAbsolute();
+}
+
 bool StyleFetchedImageSet::canRender(const LayoutObject& layoutObject, float multiplier) const
 {
     return m_bestFitImage->canRender(layoutObject, multiplier);