WebIDL/valid/idl/partial-interface.widl - external/github.com/web-platform-tests/wpt - Git at Google

 interface Foo {
   attribute DOMString bar;
 };

 partial interface Foo {
   attribute DOMString quux;
 };
	interface Foo {
	attribute DOMString bar;
	};

	partial interface Foo {
	attribute DOMString quux;
	};