* Improve test coverage for `super` keyword
Add tests for SuperCall and SuperProperty, organized together in the
`test/language/expressions/super/` directory. For SuperProperty, include
tests for usage from within Object initializers and class bodies because
a different set of semantics are observable from each context.
Utilize the test generation tool to increase coverage of destructuring
assignment semantics. Previously, only destructuring assignment in the
AssignmentExpression position was tested. With this change applied, the
same tests will assert expected behavior for destructuring assignment in
`for..of` statements, as well.
A limited number of tests are applied to the `for..in` statement as
well, but due to the iteration protocol observed by that statement, many
destructuring tests are not relevant, and others cannot be automatically
generated from this format.