Reland: Reland: Implement new Blink IDL attribute [SetReference]

Source/bindings/v8/UnsafePersistent.h

Index: Source/bindings/v8/UnsafePersistent.h
diff --git a/Source/bindings/v8/UnsafePersistent.h b/Source/bindings/v8/UnsafePersistent.h
index 6f512a26f299e2689e08532e476710423266e52b..6f297b50f45fc0b8064843cb1f30db499a733bb7 100644
--- a/Source/bindings/v8/UnsafePersistent.h
+++ b/Source/bindings/v8/UnsafePersistent.h
@@ -88,6 +88,11 @@ public:
         return handle;
     }
 
+    void setReferenceFrom(const v8::Persistent<v8::Object>& parent, v8::Isolate* isolate)
+    {
+        isolate->SetReference(parent, *persistent());
+    }
+
     void dispose()
     {
         persistent()->Dispose();