You might also be interested in Microsoft ClearScript
which is hosted on GitHub and published under the Ms-Pl licence.
I am no Microsoft fanboy, but I must admit that the V8 support has about the same functionnalities as Javascript.Net, and more important, the project is still maintained. As far as I am concerned, the support for delegates also functions better than with Spidermonkey-dotnet.
ps: It also support JScript and VBScript but we were not interested by this old stuff.
ps: It is compatible with .NET 4.0 and 4.5+
