IDL: Add support for [Unscopeable] on attributes and methods

Source/core/testing/Internals.h

Index: Source/core/testing/Internals.h
diff --git a/Source/core/testing/Internals.h b/Source/core/testing/Internals.h
index 65444604c7be128b8c6ef8ec5fb5107e43f9fded..820494c94de832d2f8cb00f6f1fc2b30a95ae57a 100644
--- a/Source/core/testing/Internals.h
+++ b/Source/core/testing/Internals.h
@@ -352,6 +352,9 @@ public:
     // |useCounterId| must be one of the values from the UseCounter::Feature enum.
     bool isUseCounted(Document*, int useCounterId);
 
+    String unscopeableAttribute();
+    String unscopeableMethod();
+
 private:
     explicit Internals(Document*);
     Document* contextDocument() const;