Oilpan: have PendingScripts trace their script elements.

Source/core/dom/PendingScript.h

Index: Source/core/dom/PendingScript.h
diff --git a/Source/core/dom/PendingScript.h b/Source/core/dom/PendingScript.h
index a5c5855819c11fa1bd04f3e38f9388af6b5d1fb9..8237aa9924f1468e3d7889531f438e3dfbe84354 100644
--- a/Source/core/dom/PendingScript.h
+++ b/Source/core/dom/PendingScript.h
@@ -29,6 +29,7 @@
 #include "core/fetch/ResourceClient.h"
 #include "core/fetch/ResourceOwner.h"
 #include "core/fetch/ScriptResource.h"
+#include "platform/heap/Handle.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/TextPosition.h"
@@ -43,7 +44,8 @@ class ScriptResource;
 // A ResourcePtr alone does not prevent the underlying Resource
 // from purging its data buffer. This class holds a dummy client open for its
 // lifetime in order to guarantee that the data buffer will not be purged.
-class PendingScript : public ResourceOwner<ScriptResource> {
+class PendingScript FINAL : public ResourceOwner<ScriptResource> {
+    ALLOW_ONLY_INLINE_ALLOCATION();

[haraken, 2014/05/29 01:46:08]

I think you need to add WTF_ALLOW_INIT_WITH_MEM_FUNCTION (which specifies
canInitializeWithMemset). I wonder why this CL compiles without setting
canInitializeWithMemset, but probably is it not needed for off-heap Vectors? (In
this CL, PendingScript is used in off-heap Vectors, not on-heap Vectors.)

[sof, 2014/05/29 06:02:07]

Yes, PendingScript appears as a part object, in off-heap vectors and deques here
for a good reason. i.e., the owning/controlling script runner objects can then
safely access them when they're finalized.

Vector<> is not a garbage collected object, so it doesn't consider
canInitializeWithMemset. See the Vector.h COMPILE_ASSERT()s.

 public:
     PendingScript()
         : m_watchingForLoad(false)
@@ -90,15 +92,17 @@ public:
 
     Element* element() const { return m_element.get(); }
     void setElement(Element* element) { m_element = element; }
-    PassRefPtr<Element> releaseElementAndClear();
+    PassRefPtrWillBeRawPtr<Element> releaseElementAndClear();
 
     void setScriptResource(ScriptResource*);
 
     virtual void notifyFinished(Resource*);
 
+    void trace(Visitor*);
+
 private:
     bool m_watchingForLoad;
-    RefPtr<Element> m_element;
+    RefPtrWillBeMember<Element> m_element;
     TextPosition m_startingPosition; // Only used for inline script tags.
 };