function hasPunctuatorBefore(content, startPosition) {
  for (let i = startPosition; i > 0; i--) {
    // Try to grab at least 6 characters so we can check for `return`
    const sliceStart = Math.max(0, i - 6);
    const precedingCharacters = content.slice(sliceStart, i);
    // Skip over any ending whitespace
    if (WHITESPACE_REGEX.test(precedingCharacters)) continue;
    // Check if it's a punctuator
    return PUNCTUATOR_REGEX.test(precedingCharacters);
  }

  // The beginning of the content counts too for our purposes.
  // i.e. a script can't start with a divide symbol
  return true;
}
Look backwards from `startPosition` in `content` for an ECMAScript punctuator.
This is used to differentiate a RegExp from a divide statement.
If a punctuator immediately precedes a lone `/`, the `/` must be the start of a RegExp.

@param {string} content
@param {number} startPosition