* Add missing generators feature flags

* Generate files

* Add generators flags

* fixup! Add generators flags

* 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.

The operand of the spread operator may be an AssignmentExpression. Add
test cases which demonstrate this.

Formulate templates for the SpreadElement in an array initializer in
order to conform to existing pattern.

In order to increase the clarity of generated output, select a name for
the test case variable that is not also used by a test template.