Oilpan: revert SVG GC mixin constructor workaround.

Source/core/svg/SVGAElement.cpp

Index: Source/core/svg/SVGAElement.cpp
diff --git a/Source/core/svg/SVGAElement.cpp b/Source/core/svg/SVGAElement.cpp
index 1f26329281b9c1593ba4803cdf26e3b60603165b..003ae450f7b1febf70f32c54ae6b367b8cd59e8b 100644
--- a/Source/core/svg/SVGAElement.cpp
+++ b/Source/core/svg/SVGAElement.cpp
@@ -55,11 +55,10 @@ using namespace HTMLNames;
 
 inline SVGAElement::SVGAElement(Document& document)
     : SVGGraphicsElement(SVGNames::aTag, document)
+    , SVGURIReference(this)
     , m_svgTarget(SVGAnimatedString::create(this, SVGNames::targetAttr, SVGString::create()))
     , m_wasFocusedByMouse(false)
 {
-    SVGURIReference::initialize(this);
-
     addToPropertyMap(m_svgTarget);
 }