Function escape_json_string_simple 

pub fn escape_json_string_simple(result: &mut String, bytes: &[u8])

Append a JSON-escaped form of bytes to result.

Accepts UTF-8 or WTF-8 (QuickJS uses WTF-8 for JS strings with lone surrogates). Scans 64 bytes at a time as 8x 8-byte SWAR masks; clean strides are skipped without copying, dirty halves jump byte-to-byte via trailing_zeros. The trailing <64 bytes are swept the same way and the final <8 fall through to process_byte.