code: function isProblematicUnicodeLocation(code) {
      if (code <= 0x1F) { // Control chars
        return true;
      }
      if (code >= 0x80 && code <= 0x9F) { // Control chars
        return true;
      }
      if ((code >= 0x2000 && code <= 0x200F) || // General punctuation chars
          (code >= 0x2028 && code <= 0x202F) ||
          (code >= 0x2060 && code <= 0x206F)) {
        return true;
      }
      if (code >= 0xFFF0 && code <= 0xFFFF) { // Specials Unicode block
        return true;
      }
      switch (code) {
        case 0x7F: // Control char
        case 0xA0: // Non breaking space
        case 0xAD: // Soft hyphen
        case 0x2011: // Non breaking hyphen
        case 0x205F: // Medium mathematical space
        case 0x25CC: // Dotted circle (combining mark)
          return true;
      }
      if ((code & ~0xFF) === 0x0E00) { // Thai/Lao chars (with combining mark)
        return true;
      }
      return false;
    }
docs: Helper function for |adjustMapping|.
  @return {boolean}