DOMTokenList.add() when the underlying string is empty (detailed review of the DOM)

(This is part of my detailed review of the Document Object Model section.)

The spec says about DOMTokenList.add():

   4. Otherwise, if the last character of the DOMTokenList object's
      underlying string is not a space character, then append a U+0020
      SPACE character to the end of that string.

When the underlying string is empty, the last character is not a space  
character, and so a space will be appended, resulting in the string " x"  
if "x" was used as parameter. Is this intentional? I wouldn't expect a  
space to be appended when the underlying string is empty.

-- 
Simon Pieters
Opera Software