Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/html/HTMLFormElement.cpp

Index: Source/core/html/HTMLFormElement.cpp
diff --git a/Source/core/html/HTMLFormElement.cpp b/Source/core/html/HTMLFormElement.cpp
index 089fde6522475add928e10b5772f182147afaf8d..0c891b1e308b39d05eaf839d10280673c1d284ad 100644
--- a/Source/core/html/HTMLFormElement.cpp
+++ b/Source/core/html/HTMLFormElement.cpp
@@ -82,7 +82,12 @@ PassRefPtr<HTMLFormElement> HTMLFormElement::create(Document& document)
 
 HTMLFormElement::~HTMLFormElement()
 {
+#if !ENABLE(OILPAN)
+    // With Oilpan, either removedFrom is called or the document and
+    // form controller are dead as well and there is no need to remove
+    // this form element from it.
     document().formController().willDeleteForm(this);
+#endif

[haraken, 2014/04/24 04:18:43]

I don't think you need to do this in this CL, but you can remove
willDeleteForm(this) from the destructor and instead enable willDeleteForm(this)
in removedFrom() in non-oilpan builds. Then we don't need #if ENABLE(OILPAN) in
this file.

[Mads Ager (chromium), 2014/04/24 10:57:36]

Yeah, this is one of the changes that I would prefer not to do at this point. If
we get it wrong we can have stale pointers in the non-oilpan build which we
don't want.

 }
 
 bool HTMLFormElement::rendererIsNeeded(const RenderStyle& style)
@@ -160,6 +165,9 @@ void HTMLFormElement::removedFrom(ContainerNode* insertionPoint)
         }
     }
     HTMLElement::removedFrom(insertionPoint);
+#if ENABLE(OILAPN)
+    document().formController().willDeleteForm(this);
+#endif

[haraken, 2014/04/24 04:18:43]

I'd put this before calling HTMLElement::removedFrom(). We normally make
SuperClass::removedFrom() as the last call.

[Mads Ager (chromium), 2014/04/24 10:57:36]

Done.

 }
 
 void HTMLFormElement::handleLocalEvents(Event* event)