Convert British English to US English per W3C Style guidelines.

Author: msporny

index.html

@@ -3908,10 +3908,10 @@ <h3>Reserved Extension Points</h3>
 
         <p>
 This specification reserves a number of [=properties=] to serve as possible
-extension points. While some implementers signalled interest in these properties,
+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, whilst others were not. It is important to note that none of these
+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.
         </p>