Update interfaces/deprecation-reporting.idl (#25812)

Source: https://github.com/w3c/webref/blob/7bbe71e/ed/idl/deprecation-reporting.idl
Build: https://travis-ci.org/w3c/webref/builds/187005808
diff --git a/interfaces/deprecation-reporting.idl b/interfaces/deprecation-reporting.idl
index 72622be..4cf76ba 100644
--- a/interfaces/deprecation-reporting.idl
+++ b/interfaces/deprecation-reporting.idl
@@ -7,7 +7,7 @@
 interface DeprecationReportBody : ReportBody {
   [Default] object toJSON();
   readonly attribute DOMString id;
-  readonly attribute Date? anticipatedRemoval;
+  readonly attribute object? anticipatedRemoval;
   readonly attribute DOMString message;
   readonly attribute DOMString? sourceFile;
   readonly attribute unsigned long? lineNumber;