bindings: Makes almost all attributes accessor-type properties.

Source/core/dom/XMLDocument.idl

Index: Source/core/dom/XMLDocument.idl
diff --git a/Source/core/dom/XMLDocument.idl b/Source/core/dom/XMLDocument.idl
index df60667a5633e399ad96862969645bb23c1bd432..db3ce53a1094c35e500417ffe359fbfed827a3ca 100644
--- a/Source/core/dom/XMLDocument.idl
+++ b/Source/core/dom/XMLDocument.idl
@@ -26,4 +26,11 @@
 // https://dom.spec.whatwg.org/#xmldocument
 
 interface XMLDocument : Document {
+    // Inheritance of [Unforgeable] attributes is not supported.  So we have to
+    // define the same unforgeable attributes in derived interfaces as well.
+    // See that Document already defined 'location' attribute and this interface
+    // redefine it.
+    // Keep all the definitions consistent.
+    // TODO(yukishiino): Support inheritance of attributes defined on instance.
+    [PutForwards=href, Unforgeable] readonly attribute Location? location;
 };