Fix Typo explicitly. Fixes #19971

    get_context_data on the super class. When no two classes try to define the

    same key, this will give the expected results. However if any class

    attempts to override a key after parent classes have set it (after the call

    to super), any children of that class will also need to explictly set it

    to super), any children of that class will also need to explicitly set it

    after super if they want to be sure to override all parents. If you're

    having trouble, review the method resolution order of your view.