Replace RenderArena with PartitionAlloc.

Source/core/html/shadow/SliderThumbElement.cpp

Index: Source/core/html/shadow/SliderThumbElement.cpp
diff --git a/Source/core/html/shadow/SliderThumbElement.cpp b/Source/core/html/shadow/SliderThumbElement.cpp
index f3124cd6bb2722911e9abbc6c5095234cccb5269..85fbe1970660f4d84e54f63e01cb0d30e2053c53 100644
--- a/Source/core/html/shadow/SliderThumbElement.cpp
+++ b/Source/core/html/shadow/SliderThumbElement.cpp
@@ -220,9 +220,9 @@ void SliderThumbElement::setPositionFromValue()
         renderer()->setNeedsLayout(true);
 }
 
-RenderObject* SliderThumbElement::createRenderer(RenderArena* arena, RenderStyle*)
+RenderObject* SliderThumbElement::createRenderer(RenderStyle*)
 {
-    return new (arena) RenderSliderThumb(this);
+    return new RenderSliderThumb(this);
 }
 
 bool SliderThumbElement::isDisabledFormControl() const
@@ -448,9 +448,9 @@ PassRefPtr<SliderContainerElement> SliderContainerElement::create(Document* docu
     return adoptRef(new SliderContainerElement(document));
 }
 
-RenderObject* SliderContainerElement::createRenderer(RenderArena* arena, RenderStyle*)
+RenderObject* SliderContainerElement::createRenderer(RenderStyle*)
 {
-    return new (arena) RenderSliderContainer(this);
+    return new RenderSliderContainer(this);
 }
 
 const AtomicString& SliderContainerElement::shadowPseudoId() const