Make CSSParserContext be garbage collected.

third_party/WebKit/Source/web/WebDocument.cpp

Index: third_party/WebKit/Source/web/WebDocument.cpp
diff --git a/third_party/WebKit/Source/web/WebDocument.cpp b/third_party/WebKit/Source/web/WebDocument.cpp
index 9ccdab7054afa2e9233b855efea3dbb26a82eff5..c233eef22f4bdc60a90f9d95e024e0377571c647 100644
--- a/third_party/WebKit/Source/web/WebDocument.cpp
+++ b/third_party/WebKit/Source/web/WebDocument.cpp
@@ -186,7 +186,7 @@ void WebDocument::insertStyleSheet(const WebString& sourceCode) {
   Document* document = unwrap<Document>();
   DCHECK(document);
   StyleSheetContents* parsedSheet =
-      StyleSheetContents::create(CSSParserContext(*document, nullptr));
+      StyleSheetContents::create(CSSParserContext::create(*document));
   parsedSheet->parseString(sourceCode);
   document->styleEngine().injectAuthorSheet(parsedSheet);
 }