Rename "inherit state" for spellcheck=""

The spellcheck attribute's missing value default is called the "inherit state":

   The inherit state indicates that the element is to act the same way as
   its parent.
    -- http://www.whatwg.org/specs/web-apps/current-work/multipage/editing.html#spelling-and-grammar-checking

But this does not match the spec's requirements: the inherit state depends on the default behavior, and thus it would be clearer if it was renamed to the "default state" and the paragraph above changed accordingly.

-- 
Simon Pieters
Opera Software