Type check when upcasting PassOwnPtr/PassOwnArrayPtr to avoid possible function call ambiguousness

Source/wtf/PassOwnArrayPtr.h

Index: Source/wtf/PassOwnArrayPtr.h
diff --git a/Source/wtf/PassOwnArrayPtr.h b/Source/wtf/PassOwnArrayPtr.h
index 724dba3bf41e4a4dffd17e97d54560ac9a6d92d1..10cbce940becfd7f327197781021d0a7d56eef73 100644
--- a/Source/wtf/PassOwnArrayPtr.h
+++ b/Source/wtf/PassOwnArrayPtr.h
@@ -30,6 +30,11 @@
 #include "wtf/NullPtr.h"
 #include "wtf/TypeTraits.h"
 
+#define EnsureOwnArrayPtrConvertibleArgDefn \
+    typename EnableIf<IsPointerConvertible<U, T>::Value, bool>::Type
+#define EnsureOwnArrayPtrConvertibleArgDecl \
+    EnsureOwnArrayPtrConvertibleArgDefn = true
+
 namespace WTF {
 
 template<typename T> class OwnArrayPtr;
@@ -49,7 +54,7 @@ public:
     // a const PassOwnArrayPtr. However, it makes it much easier to work with PassOwnArrayPtr
     // temporaries, and we don't have a need to use real const PassOwnArrayPtrs anyway.
     PassOwnArrayPtr(const PassOwnArrayPtr& o) : m_ptr(o.leakPtr()) { }
-    template<typename U> PassOwnArrayPtr(const PassOwnArrayPtr<U>& o) : m_ptr(o.leakPtr()) { }
+    template<typename U> PassOwnArrayPtr(const PassOwnArrayPtr<U>& o, EnsureOwnArrayPtrConvertibleArgDecl) : m_ptr(o.leakPtr()) { }
 
     ~PassOwnArrayPtr() { deleteOwnedArrayPtr(m_ptr); }