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

Source/core/style/StyleGeneratedImage.cpp

Index: Source/core/style/StyleGeneratedImage.cpp
diff --git a/Source/core/style/StyleGeneratedImage.cpp b/Source/core/style/StyleGeneratedImage.cpp
index fff63c74437c584b51b40ef7fedef448df0a4949..4fca6ef593f0d16c1c7470eb27ad7ef2454bee33 100644
--- a/Source/core/style/StyleGeneratedImage.cpp
+++ b/Source/core/style/StyleGeneratedImage.cpp
@@ -42,6 +42,11 @@ PassRefPtrWillBeRawPtr<CSSValue> StyleGeneratedImage::cssValue() const
     return m_imageGeneratorValue.get();
 }
 
+PassRefPtrWillBeRawPtr<CSSValue> StyleGeneratedImage::computedCSSValue() const
+{
+    return m_imageGeneratorValue->valueWithURLMadeAbsolute();
+}
+
 LayoutSize StyleGeneratedImage::imageSize(const LayoutObject* layoutObject, float multiplier) const
 {
     if (m_fixedSize) {