[whatwg] handler URI escaping in 4.5.1 appears to be different from encodeURIComponent

[Dan Mosedale]

The escaping specified in 
<http://www.whatwg.org/specs/web-apps/current-work/#custom-handlers> is 
slightly different than the escaping done by encodeURIComponent (as 
described at 
<http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Global_Functions:encodeURIComponent>).   
Specifically, encodeURIComponent is documented as not escaping:

    ! * ' ( )

characters, whereas the spec seems to want these characters to be 
escaped.  Is this intentional?  If so, what's the motivation?

Dan