Fix bugs in test/editor.html

This is for `test/editor.html`

1ca0d54 is to fix "When select `dijit/form/Checkbox` component type and enable autoSave, the checkboxes are not be able to unchecked."

6eceff6 is to fix "Error occurred when change component type from `dijit/form/SimpleTextarea` to `dijit/form/Checkbox`."


ps. This is my first pull request, so please advise if there is anything wrong.