Oilpan: Make sure that vtables for garbage collected mixin objects have

Source/core/html/forms/TextFieldInputType.h

Index: Source/core/html/forms/TextFieldInputType.h
diff --git a/Source/core/html/forms/TextFieldInputType.h b/Source/core/html/forms/TextFieldInputType.h
index 0eb1fda2d4c9eea5e1180696753a1fb72a288eac..769c5e751aed8b1224eedc427be6e408e6e2da7c 100644
--- a/Source/core/html/forms/TextFieldInputType.h
+++ b/Source/core/html/forms/TextFieldInputType.h
@@ -42,6 +42,9 @@ class FormDataList;
 // It supports not only the types for BaseTextInputType but also type=number.
 class TextFieldInputType : public InputType, protected SpinButtonElement::SpinButtonOwner {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(TextFieldInputType);
+public:
+    virtual void trace(Visitor* visitor) OVERRIDE { InputType::trace(visitor); }
+
 protected:
     TextFieldInputType(HTMLInputElement&);
     virtual ~TextFieldInputType();
@@ -49,7 +52,6 @@ protected:
     virtual void handleKeydownEvent(KeyboardEvent*) OVERRIDE;
     void handleKeydownEventForSpinButton(KeyboardEvent*);
 
-protected:
     virtual bool needsContainer() const { return false; }
     bool shouldHaveSpinButton() const;
     virtual void createShadowSubtree() OVERRIDE;