[IE] DispHTMLAttributeCollection doesn't have getAttribute() method

[pomu0325]

At line.726 of dom/element.js, it calls getAttribute method of thisAttribs(instance of DispHTMLAttributeCollection), but it fails. Instead, item() method should be used.

if ( ( !CKEDITOR.env.ie || ( attribute.specified && attribute.nodeName != '_cke_expando' ) )
 && attribute.nodeValue != thisAttribs.getAttribute( attribute.nodeName ) )

To reproduce this error,

• Add following settings to config.js

  CKEDITOR.editorConfig = function( config )
  {
      config.coreStyles_bold = 
      { 
  		element : 'span',
  		attributes	: { 'class' : 'foo' },
  		overrides : 'b'
       };
  
      config.coreStyles_italic =
      { 
  		element : 'span',
  		attributes	: { 'class' : 'bar' },
  		overrides : 'i'
       };
  };
  

• Open any sample page of CKEditor
• Type some text in editor
• Select these text
• Click 'B'(bold) button from the toolbar
• Click 'I'(italic) button from the toolbar twice

[garry.yao]

Providing a patch based on pomu's patch. Ticket Test added at :
​http://ckeditor.t/tt/4597/1.html.

[garry.yao]

Fixed with [4495].