Oilpan: Prepare to move UA shadow elemnts for date/time input types to Oilpan heap.

Source/core/html/forms/BaseMultipleFieldsDateAndTimeInputType.h

Index: Source/core/html/forms/BaseMultipleFieldsDateAndTimeInputType.h
diff --git a/Source/core/html/forms/BaseMultipleFieldsDateAndTimeInputType.h b/Source/core/html/forms/BaseMultipleFieldsDateAndTimeInputType.h
index 70ee1ae38205acd9084c57c26cc83fb33fc3d618..4867175784d51b095b9c6304e8aafa5ea40dc494 100644
--- a/Source/core/html/forms/BaseMultipleFieldsDateAndTimeInputType.h
+++ b/Source/core/html/forms/BaseMultipleFieldsDateAndTimeInputType.h
@@ -49,6 +49,8 @@ class BaseMultipleFieldsDateAndTimeInputType
     , protected PickerIndicatorElement::PickerIndicatorOwner
     , protected SpinButtonElement::SpinButtonOwner
     , protected ClearButtonElement::ClearButtonOwner {
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(BaseMultipleFieldsDateAndTimeInputType);
+
 public:
     virtual bool isValidFormat(bool hasYear, bool hasMonth, bool hasWeek, bool hasDay, bool hasAMPM, bool hasHour, bool hasMinute, bool hasSecond) const = 0;