node.setAttribute导致INVALID_CHARACTER_ERR

  this.HtmlRef = document.createElement( \"canvas\" );

  if (!this.HtmlRef)
  {
    return false;
  }

  this.HtmlRef.appendChild(  document.createTextNode( \"Your browser doesn\'t support dynamic graphic drawings (Canvas)!\" )  );

  var Width = document.createAttribute( \"width\" );
  var Height = document.createAttribute( \"height\" );
  Width.nodeValue = 0;
  Height.nodeValue = 0;

  this.HtmlRef.setAttribute(Width);  /* error */
  this.HtmlRef.setAttribute(Height); /* error */