Method checkUTF8

ext/src/llvm/JSON.cpp:208–214

      : Start(JSON.begin()), P(JSON.begin()), End(JSON.end()) {}

  bool checkUTF8() {
    size_t ErrOffset;
    if (isUTF8(StringRef(Start, End - Start), &ErrOffset))
      return true;
    P = Start + ErrOffset; // For line/column calculation.
    return parseError("Invalid UTF-8 sequence");
  }

  bool parseValue(Value &Out);