Oilpan: fix build after r194987.

Source/core/html/HTMLContentElement.cpp

Index: Source/core/html/HTMLContentElement.cpp
diff --git a/Source/core/html/HTMLContentElement.cpp b/Source/core/html/HTMLContentElement.cpp
index a4f7c9f57abebd5fd3f32f685c978a736d0dbfb8..6399f36330458d97b7f1bd3e71b5b10f95c76834 100644
--- a/Source/core/html/HTMLContentElement.cpp
+++ b/Source/core/html/HTMLContentElement.cpp
@@ -40,6 +40,11 @@ namespace blink {
 
 using namespace HTMLNames;
 
+PassRefPtrWillBeRawPtr<HTMLContentElement> HTMLContentElement::create(Document& document, PassOwnPtrWillBeRawPtr<HTMLContentSelectFilter> filter)
+{
+    return adoptRefWillBeNoop(new HTMLContentElement(document, filter));
+}
+
 inline HTMLContentElement::HTMLContentElement(Document& document, PassOwnPtrWillBeRawPtr<HTMLContentSelectFilter> filter)
     : InsertionPoint(contentTag, document)
     , m_shouldParseSelect(false)
@@ -48,13 +53,14 @@ inline HTMLContentElement::HTMLContentElement(Document& document, PassOwnPtrWill
 {
 }
 
-PassRefPtrWillBeRawPtr<HTMLContentElement> HTMLContentElement::create(Document& document, PassOwnPtrWillBeRawPtr<HTMLContentSelectFilter> filter)
+HTMLContentElement::~HTMLContentElement()
 {
-    return adoptRefWillBeNoop(new HTMLContentElement(document, filter));
 }
 
-HTMLContentElement::~HTMLContentElement()
+DEFINE_TRACE(HTMLContentElement)
 {
+    visitor->trace(m_filter);
+    InsertionPoint::trace(visitor);
 }
 
 void HTMLContentElement::parseSelect()