MAGETWO-70181: Allow option disabling for optgroup binding #10031

Author: Oleksii Korshenko

app/code/Magento/Ui/view/base/web/js/lib/knockout/bindings/optgroup.js

@@ -297,11 +297,16 @@ define([
                 ko.utils.arrayForEach(options, function (option) {
                     var value = applyToObject(option, optionsValue, option),
                         label = applyToObject(option, optionsText, value) || '',
+                        disabled = applyToObject(option, 'disabled', false) || false,
                         obj = {},
                         space = '\u2007\u2007\u2007';
 
                     obj[optionTitle] = applyToObject(option, optionsText + 'title', value);
 
+                    if (disabled) {
+                        obj.disabled = disabled;
+                    }
+
                     label = label.replace(nbspRe, '').trim();
 
                     if (Array.isArray(value)) {