Oilpan: move SVG property hierarchy to the heap.

Source/core/svg/SVGAnimatedNumber.idl

 /*
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  * Copyright (C) 2006 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 12 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 [
     NotScriptWrappable,
     SetWrapperReferenceTo(SVGElement contextElement),
     TypeChecking=Interface,
     RuntimeEnabled=SVG1DOM,
     MeasureAs=SVG1DOM,
+    WillBeGarbageCollected,
 ] interface SVGAnimatedNumber {
     [RaisesException=Setter] attribute float baseVal;
     readonly attribute float animVal;
 };