Oilpan: move 2D Canvas and WebGL objects to the heap.

Source/bindings/core/v8/Nullable.h

Index: Source/bindings/core/v8/Nullable.h
diff --git a/Source/bindings/core/v8/Nullable.h b/Source/bindings/core/v8/Nullable.h
index ad175a97efac47a8c5c8e129a85ceea2e830d1c0..26f1d086f26ab0c052c11f67bf73ffcd6aa560ed 100644
--- a/Source/bindings/core/v8/Nullable.h
+++ b/Source/bindings/core/v8/Nullable.h
@@ -5,12 +5,14 @@
 #ifndef Nullable_h
 #define Nullable_h
 
+#include "platform/heap/Handle.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 template <typename T>
 class Nullable {
+    DISALLOW_ALLOCATION();
 public:
     Nullable()
         : m_value()
@@ -41,6 +43,11 @@ public:
         return (m_isNull && other.m_isNull) || (!m_isNull && !other.m_isNull && m_value == other.m_value);
     }
 
+    void trace(Visitor* visitor)
+    {
+        TraceIfNeeded<T>::trace(visitor, &m_value);
+    }
+
 private:
     T m_value;
     bool m_isNull;