Prevent adding quotes if there's a numeric literal as key

[duailibe]

// input
foo = {
  a: 1,
  1: 1,
};

// output (before)
foo = {
  "a": 1,
  1: 1,
};

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[duailibe]

Note: this still happens

// input
foo = {
  a: 1,
  "1": 1,
};

// output
foo = {
  "a": 1,
  "1": 1,
};