Maxlength attribute broken

[devbranch-vadym]

Placeholders.js code accesses maxlength attribute using the object notation in the showPlaceholder:

      if ( !maxLength ) {
        elem.setAttribute(ATTR_MAXLENGTH, elem.maxLength);
        elem.removeAttribute('maxLength');
      }

The code is case sensitive and fetches attribute value as undefined if it's named in some other manner like maxlength or MAXLENGTH (at least for IE8).

The undefined value is then written back in the hidePlaceholder.

[devbranch-vadym]

Pull request #107 .