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 0f8356c472d399a03fad26c4fcbcda01f3f8ce64..576c0e3ac6f061b568f67d647807080268f5729f 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 WebCore {
 
 template <typename T>
 class Nullable {
+    DISALLOW_ALLOCATION();
 public:
     Nullable()
         : m_value()
@@ -41,6 +43,12 @@ public:
         return (m_isNull && other.m_isNull) || (!m_isNull && !other.m_isNull && m_value == other.m_value);
     }
 
+    void trace(Visitor*)
+    {
+        // FIXME: candidate for EnableIf<> and NeedsTracing<>, somehow ?

[sof, 2014/07/12 07:22:09]

When rebasing past r177935's addition of Nullable<> as a return type for
getAttachedShaders(), I noticed that Nullable doesn't handle traceable values.

We need to include a trace() method depending on the nullable's type; the
workaround here just provides it always (and doesn't do much tracing, just
keeping the GC plugin checks quiet.)

I also annotated the class with DISALLOW_ALLOCATION().

+        (void)m_value;
+    }
+
 private:
     T m_value;
     bool m_isNull;