Oilpan: move DOM string collection objects to the Oilpan heap.

Source/core/dom/DatasetDOMStringMap.cpp

Index: Source/core/dom/DatasetDOMStringMap.cpp
diff --git a/Source/core/dom/DatasetDOMStringMap.cpp b/Source/core/dom/DatasetDOMStringMap.cpp
index 8690449f86314d26cc57d9bed216cec09c41e1c0..adf09b1210c860ef3b7e804cce7cd3b0eb74969e 100644
--- a/Source/core/dom/DatasetDOMStringMap.cpp
+++ b/Source/core/dom/DatasetDOMStringMap.cpp
@@ -140,6 +140,7 @@ static AtomicString convertPropertyNameToAttributeName(const String& name)
     return builder.toAtomicString();
 }
 
+#if !ENABLE(OILPAN)
 void DatasetDOMStringMap::ref()
 {
     m_element->ref();
@@ -149,6 +150,7 @@ void DatasetDOMStringMap::deref()
 {
     m_element->deref();
 }
+#endif
 
 void DatasetDOMStringMap::getNames(Vector<String>& names)
 {
@@ -215,4 +217,10 @@ bool DatasetDOMStringMap::deleteItem(const String& name)
     return false;
 }
 
+void DatasetDOMStringMap::trace(Visitor* visitor)
+{
+    visitor->trace(m_element);

[Mads Ager (chromium), 2014/04/29 09:05:14]

Yeah, since you are tracing m_element, please put it in a Member. We should stay
away from tracing raw pointers when we can. If I see a raw pointer that is not
in a union I will assume that it is not traced. 

+    DOMStringMap::trace(visitor);
+}
+
 } // namespace WebCore