Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

Set a proper length reference to avoid conflict with browsers

In browsers length is a valid property of window, so they would have a normal
completion instead of a ReferenceError

* Add tests for Promises rejection queue

These basic tests assert the rejection is captured but a later queued job
from a chain of then calls.

* fixup! Add tests for Promises rejection queue

Expression statement lookahead restriction and identifier tests

Lexical redeclarations in block- and switch-statements

Background feedback from @anba:

In https://tc39.github.io/ecma262/#sec-switch-statement-static-semantics-lexicallydeclarednames, all lexically declared names from the different case clauses are combined.
For each case clause, the LexicallyDeclaredNames definition from https://tc39.github.io/ecma262/#sec-block-static-semantics-lexicallydeclarednames applies, which has:

```
StatementListItem : Declaration
  1. Return the BoundNames of Declaration.
```

And in https://tc39.github.io/ecma262/#prod-Declaration we've got:

```
Declaration[Yield, Await] : HoistableDeclaration[?Yield, ?Await, ~Default]
```

And in https://tc39.github.io/ecma262/#prod-HoistableDeclaration:

```
HoistableDeclaration[Yield, Await, Default] : FunctionDeclaration[?Yield, ?Await, ?Default]
```

And the BoundNames of a FunctionDeclaration is its BindingIdentifier https://tc39.github.io/ecma262/#sec-function-definitions-static-semantics-boundnames.

And there's also B3.3.5 (https://tc39.github.io/ecma262/#sec-switch-duplicates-allowed-static-semantics) which allows duplicate FunctionDeclarations in sloppy mode in switch-statements.

Switch to assert-lib in intl402

for-await-of: dstr-binding, async func & async gen templates

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

Ref. https://github.com/mathiasbynens/unicode-property-escapes-tests/pull/8.