Format of v8 log file changed in v15

[pbadenski]

So far I noticed this for IC info - row, column and map fields are not read property. I don't mind submitting pull request, but need a bit of guidance:

• is there a place where I can look this format up - there seems to be a new field there and I don't know what it is
• is there a way to specify different parser and separate code paths for log files dumped by node v15