Change CSSParserContext to have a Document handle (vs UseCounter).

third_party/WebKit/Source/core/css/CSSStyleSheet.cpp

Index: third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp b/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
index c7ddcfa2f93aa39ffb5f0ac3a01d505b64fc4d62..22d89cc955a62693ca24005d59aeb651d33146fa 100644
--- a/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
+++ b/third_party/WebKit/Source/core/css/CSSStyleSheet.cpp
@@ -80,6 +80,14 @@ static bool isAcceptableCSSStyleSheetParent(const Node& parentNode) {
 }
 #endif
 
+// static
+const Document* CSSStyleSheet::singleOwnerDocument(
+    const CSSStyleSheet* styleSheet) {
+  if (styleSheet)
+    return StyleSheetContents::singleOwnerDocument(styleSheet->contents());
+  return nullptr;
+}
+
 CSSStyleSheet* CSSStyleSheet::create(StyleSheetContents* sheet,
                                      CSSImportRule* ownerRule) {
   return new CSSStyleSheet(sheet, ownerRule);