Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/svg/SVGElement.cpp

Index: Source/core/svg/SVGElement.cpp
diff --git a/Source/core/svg/SVGElement.cpp b/Source/core/svg/SVGElement.cpp
index fdfd69b08660c578cce3ca5d218f0c6adb573abf..25dc280b010d76ab84fdca2cb63bf84a8fedfe81 100644
--- a/Source/core/svg/SVGElement.cpp
+++ b/Source/core/svg/SVGElement.cpp
@@ -113,8 +113,12 @@ SVGElement::~SVGElement()
         // removeAllElementReferencesForTarget() below.
         clearHasSVGRareData();
     }
+#if !ENABLE(OILPAN)
+    // With Oilpan, either removedFrom has been called or the document is dead
+    // as well and there is no reason to clear out the extensions.
     document().accessSVGExtensions().rebuildAllElementReferencesForTarget(this);
     document().accessSVGExtensions().removeAllElementReferencesForTarget(this);
+#endif
 }
 
 void SVGElement::willRecalcStyle(StyleRecalcChange change)