Duplicate PropertyName of `__proto__` should be accepted in destructuring

Annex B defines an early error for duplicate PropertyName of __proto__, in object initializers, but this does not apply to Object Assignment patterns

Steps to reproduce

esprima.parse('result = { __proto__: x, __proto__: y } = value;')

// Parenthesized
esprima.parse('result = ({ __proto__: x, __proto__: y } = value);')

Expected output

{
    "type": "Program",
    "body": [
        {
            "type": "ExpressionStatement",
            "expression": {
                "type": "AssignmentExpression",
                "left": {
                    "type": "Identifier",
                    "name": "result"
                },
                "operator": "=",
                "right": {
                    "type": "AssignmentExpression",
                    "left": {
                        "type": "ObjectPattern",
                        "properties": [
                            {
                                "type": "Property",
                                "key": {
                                    "type": "Identifier",
                                    "name": "__proto__"
                                },
                                "value": {
                                    "type": "Identifier",
                                    "name": "x"
                                },
                                "kind": "init",
                                "computed": false,
                                "method": false,
                                "shorthand": false
                            },
                            {
                                "type": "Property",
                                "key": {
                                    "type": "Identifier",
                                    "name": "__proto__"
                                },
                                "value": {
                                    "type": "Identifier",
                                    "name": "y"
                                },
                                "kind": "init",
                                "computed": false,
                                "method": false,
                                "shorthand": false
                            }
                        ]
                    },
                    "operator": "=",
                    "right": {
                        "type": "Identifier",
                        "name": "value"
                    }
                }
            }
        }
    ],
    "sourceType": "script"
}

Actual output

Throws Error: Line 1: Duplicate __proto__ fields are not allowed in object literals

Relevant references

There exist an Test262 test for this

Start with the parser path for object assignment patterns and the duplicate proto validation, using the esprima.parse reproducer in this issue. Compare its behavior with the linked Test262 case and verify that both examples parse into the shown nested AssignmentExpression and ObjectPattern AST without an error.