Oilpan: fix build after r181536.

TBR=oilpan-reviews
BUG=367689
NOTRY=true

Review URL: https://codereview.chromium.org/547323002

git-svn-id: svn://svn.chromium.org/blink/trunk@181544 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/xml/XSLStyleSheetLibxslt.cpp

@@ -329,6 +329,7 @@ void XSLStyleSheet::trace(Visitor* visitor)
     visitor->trace(m_ownerNode);
     visitor->trace(m_children);
     visitor->trace(m_parentStyleSheet);
+    visitor->trace(m_ownerDocument);
     StyleSheet::trace(visitor);
 }
 

third_party/WebKit/Source/core/xml/XSLTProcessor.cpp

@@ -162,6 +162,7 @@ void XSLTProcessor::trace(Visitor* visitor)
 {
     visitor->trace(m_stylesheet);
     visitor->trace(m_stylesheetRootNode);
+    visitor->trace(m_document);
 }
 
 } // namespace blink