Move IsPointerConvertible<T, JSONValue> specialization out of TypeTraits.h

Source/wtf/TypeTraits.h

Index: Source/wtf/TypeTraits.h
diff --git a/Source/wtf/TypeTraits.h b/Source/wtf/TypeTraits.h
index 3dfcc31793fa43ccdf0d492016d3aa57eb78323d..4946ef5d39e9f631a72c43393362b7804fd0f0c2 100644
--- a/Source/wtf/TypeTraits.h
+++ b/Source/wtf/TypeTraits.h
@@ -302,22 +302,12 @@ namespace WTF {
 
 namespace blink {
 
-class JSONValue;
 class Visitor;
 
 } // namespace blink
 
 namespace WTF {
 
-    // FIXME: Disable pointer conversion checking against JSONValue.
-    // The current CodeGeneratorInspector.py generates code which upcasts to JSONValue from undefined types.
-    template<typename From> class IsPointerConvertible<From, blink::JSONValue> {
-    public:
-        enum {
-            Value = true
-        };
-    };
-
 template<typename T>
 class NeedsTracing {
     typedef char YesType;