I've seen a day ago a recording of a presentation from last week FOSDEM where two other libraries, Lorca[0] (Go + HTML5) and Webview[1] (C++/C/Go), were described that are similar in scope to this one.
From the webview project page: It supports two-way JavaScript bindings (to call JavaScript from C/C++/Go and to call C/C++/Go from JavaScript). It uses Cocoa/WebKit on macOS, gtk-webkit2 on Linux and MSHTML (IE10/11) on Windows.