[oilpan] Completely move HTMLFormControlElement's hierarchy to the managed heap

Source/core/rendering/RenderButton.cpp

Index: Source/core/rendering/RenderButton.cpp
diff --git a/Source/core/rendering/RenderButton.cpp b/Source/core/rendering/RenderButton.cpp
index d5cf64b681423756ff4004d142a2fcb29254b065..cf2eb625479541ca41d30597ac84afb24d2dd924 100644
--- a/Source/core/rendering/RenderButton.cpp
+++ b/Source/core/rendering/RenderButton.cpp
@@ -112,7 +112,7 @@ void RenderButton::updateFromElement()
 {
     // If we're an input element, we may need to change our button text.
     if (node()->hasTagName(inputTag)) {
-        HTMLInputElement* input = static_cast<HTMLInputElement*>(node());
+        Handle<HTMLInputElement> input(static_cast<HTMLInputElement*>(node()));
         String value = input->valueWithDefault();
         setText(value);
     }