Refactor root element background painting

Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp

Index: Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
diff --git a/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp b/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
index 90be49fbb85bc777b2d4e1fc38fa4a26e3f689f9..1cb32581767e9ae18a70b06d79d7159086eff8f9 100644
--- a/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
+++ b/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
@@ -1740,11 +1740,7 @@ float CompositedDeprecatedPaintLayerMapping::compositingOpacity(float layoutObje
 
 Color CompositedDeprecatedPaintLayerMapping::layoutObjectBackgroundColor() const
 {
-    LayoutObject* backgroundLayoutObject = layoutObject();
-    if (backgroundLayoutObject->isDocumentElement())
-        backgroundLayoutObject = backgroundLayoutObject->layoutObjectForRootBackground();
-
-    return backgroundLayoutObject->resolveColor(CSSPropertyBackgroundColor);
+    return layoutObject()->resolveColor(CSSPropertyBackgroundColor);
 }
 
 void CompositedDeprecatedPaintLayerMapping::updateBackgroundColor()