Unnecessary binding

[sofiapoh]

https://github.com/fac-12/Lex/blob/3f591db5c8a96556abc357c622929633afc5adf3/src/components/App.js#L54

and

https://github.com/fac-12/Lex/blob/3f591db5c8a96556abc357c622929633afc5adf3/src/components/App.js#L56

When the functions are defined with arrow function () => {} instead of using the function keyword they have access to the context in which they were defined. In this case this refers to the App class and no binding to the context outside is needed.