[whatwg] [html5] %Pixels; unnecessary

[David Håsäther]

The Pixels parameter entity replacement text should be NUMBER instead
of CDATA since the comment says "integer representing length in
pixels".
Also, the entity is only used once in the DTD (for the BORDER
attribute of the TABLE element type) so it could as well be:
    border      NUMBER       #IMPLIED  -- controls frame width around table --

-- 
David Håsäther