private field identifier encoding causing parse error

[jdalton]

Test 262 test related fail

/* Generated from: /test/language/statements/class/elements/private-accessor-name/static-private-escape-sequence-u2118.js */
staticPrivateEscapeSequenceU2118: {
  var stringSet;
  class C {
    static get #\u2118() { return 'get string'; }
    static set #\u2118(param) { stringSet = param; }
    static getPrivateReference() {
      return this.#℘;
    }
    static setPrivateReference(value) {
      this.#℘ = value;
    }
  }
  assert.sameValue(C.getPrivateReference(), 'get string');
  C.setPrivateReference('set string');
  assert.sameValue(stringSet, 'set string');
}

and

staticPrivateEscapeSequenceU6F: {
  var stringSet;
  class C {
    static get #\u{6F}() { return 'get string'; }
    static set #\u{6F}(param) { stringSet = param; }
    static getPrivateReference() {
      return this.#o;
    }
    static setPrivateReference(value) {
      this.#o = value;
    }
  }
  assert.sameValue(C.getPrivateReference(), 'get string');
  C.setPrivateReference('set string');
  assert.sameValue(stringSet, 'set string');
}

incorrectly throws:
[9:16]: Invalid key token

[3cp]

Yet to be implemented. #214