[performance] Migrate to source-map-js

[kabachook]

https://github.com/7rulnik/source-map-js
Seems to have better performance and maintained
More context: https://t.me/valya_reads_issue/111

[neSpecc]

@robonetphy Could you try benchmarking this?

[robonetphy]

@neSpecc you can check this repo I have done basic time analysis of the both source-map and source-map-js library and also plot a graph

[neSpecc]

@neSpecc you can check this repo I have done basic time analysis of the both source-map and source-map-js library and also plot a graph

Thanks. Please provide your conclusions and screenshots.

[robonetphy]

@neSpecc Actually I can't conclude because you can check the time difference graph of TimeOf(source-map)-TimeOf(source-map-js) as follow. it's always varying while I am passing constant amount of work.
I am using performance.now() for time measurement. Let me know if there is better way.