Use TreeScope::completeURL and baseURL instead of the Document versions

Source/core/css/resolver/StyleBuilderCustom.cpp

Index: Source/core/css/resolver/StyleBuilderCustom.cpp
diff --git a/Source/core/css/resolver/StyleBuilderCustom.cpp b/Source/core/css/resolver/StyleBuilderCustom.cpp
index 411ba05315c85980ec55c7f35c67f0e4f985cb95..16656dab2fbdb3f9d5a76996c3553899122db990 100755
--- a/Source/core/css/resolver/StyleBuilderCustom.cpp
+++ b/Source/core/css/resolver/StyleBuilderCustom.cpp
@@ -660,7 +660,7 @@ void StyleBuilderFunctions::applyValueCSSPropertyWebkitClipPath(StyleResolverSta
             state.style()->setClipPath(ShapeClipPathOperation::create(basicShapeForValue(state, primitiveValue->getShapeValue())));
         } else if (primitiveValue->primitiveType() == CSSPrimitiveValue::CSS_URI) {
             String cssURLValue = primitiveValue->getStringValue();
-            KURL url = state.document().completeURL(cssURLValue);
+            KURL url = state.treeScope().completeURL(cssURLValue);
             // FIXME: It doesn't work with forward or external SVG references (see https://bugs.webkit.org/show_bug.cgi?id=90405)
             state.style()->setClipPath(ReferenceClipPathOperation::create(cssURLValue, AtomicString(url.fragmentIdentifier())));
         }