Remove outdated sentence about previous registrations.

index.html

@@ -3880,11 +3880,10 @@ <h3>Reserved Extension Points</h3>
         <p>
 This specification reserves a number of [=properties=] to serve as possible
 extension points. While some implementers signaled interest in these properties,
-their inclusion in this specification was considered to be premature. Some of
-these extension points were originally defined in previous versions of this
-specification, while others were not. It is important to note that none of these
-properties are defined by this specification. Consequently, implementers are
-cautioned that use of these properties is considered experimental.
+their inclusion in this specification was considered to be premature. It is
+important to note that none of these properties are defined by this
+specification. Consequently, implementers are cautioned that use of these
+properties is considered experimental.
         </p>
         <p>
 Implementers MAY use these properties, but SHOULD expect them and/or