This is a former research project looking into the readiness of parallelism in JavaScript after Intel created the River Trail project (https://intellabs.github.io/RiverTrail/tutorial/).
This was origninally intended to be a section of a paper which can be found here: http://dig.cs.illinois.edu/papers/radoi_HICSS50.pdf
Unfortunately, both the Firefox and Intel developers agreed that this never gave performance improvements (largely because the JIT compiler didn't play well with parallelism).
Intel Labs has since labeled the project as having security holes: https://github.com/IntelLabs/RiverTrail
Thanks for visiting! :)