missing = in const declaration

[Akkuma]

https://github.com/mathiasbynens/jsesc/blob/30be7a62d862d8b5b49ffc4424a10c85f0ee6f6d/src/jsesc.js#L6 causes Firefox to throw the above error, which can be reproduced by pasting this into Firefox's console.

for (const key in {t:1,x:1}) {
  if (hasOwnProperty.call(object, key)) {
    console.log('Never reaches as the code errors');
  }
}

This makes jsesc unusable with webpack/browserify in those environments without explicitly converting the es6 code into es5.

[mathiasbynens]

https://github.com/mathiasbynens/jsesc#support