First set of tests for Top Level Await

[leobalter]

First goal here is to cover syntax tests for:

ModuleItem : StatementListItem[~Yield, +Await, ~Return]

ExportDeclaration :
  export VariableStatement[~Yield, +Await]
  export Declaration[~Yield, +Await]
  export default HoistableDeclaration[~Yield, +Await, +Default]
  export default ClassDeclaration[~Yield, +Await, +Default]
  export default [lookahead ∉ { function, async [no LineTerminator here] function, class }] AssignmentExpression[+In, ~Yield, ~Await] ;

[rwaldron]

Approved the first 2 commits

[rwaldron]

😆 love it.

[rwaldron]

🤣

[rwaldron]

I fixed this locally, rebased and merged into master.