Prent node is not check if children are checked and disabled

[mhascak]

Hello I have problem.

Parent node is not checked if children nodes are checked and also makred as disabled.
If I remove disabled flag parent node is checked correctly.

Problem reproduction example:

FIDDLE - https://jsfiddle.net/s80hajmg/

  function getTreeData() {
    	return [
          {
            displayName: 'JS: The Right Way',
            state: { expanded: true, **disabled: true**  },
            children: [
              { displayName: 'Getting Started', state: { checked: true, **disabled: true** } },
              { displayName: 'JavaScript Code Style', state: { selected: true, **disabled: true**  } }
            ]
          }
        ]
    }

[amsik]

Hello! Disabled nodes are skipped in the calculation of parent checked status. Need to think about this: do not skip the check or add a new tree's property.