Project: survey
Task (easy): Class SurveyDesign constructor params are: formSelector (string), title (string). Method 'prependQuestion(question)' and 'appendQuestion(question)' are used to prepend/append a 'question.root' to the form (got by param 'formSelector'). Save codes to 'common/SurveyDesign.js' imported by 'design.js'. Move '.add-question' button codes to 'common/SurveyDesign.js' which should import './Question.js'.