Yes, at first it reminds me a bit of Haxe [0], which compiles to a multitude of languages. Originally it was made to "replace" JavaScript, there's Angular Dart for instance as an example of what that would work like. But nowadays Dart can compile to JavaScript or "Dart Native" [2] which instead of Haxe reminds much more of Java or C# since it runs inside a VM in JIT mode.
It can run on ARM32, ARM64 and x84_64 natively as machine code through the Dart runtime when compiled AOT and performance is of course much better than compiling to JavaScript so you can see why it's a really interesting option for the development of Flutter which targets web, desktop, and mobile. You write the code once and get to have JIT for development with hot reloading, debugging and live metrics, and AOT compilation for your desktop and mobile targets while also getting a JavaScript bundle for your web target.
Originally it was built on top of v8 itself if I'm not mistaekn, so the author might be referencing some historical knowledge that has kind of changed.
Seems I too may be misremembering as well, I do know there used to be a custom Chromium build that included a Dart runtime so I assumed that was why v8 was used. But I remember now, there was an original effort to include dart in Chrome which met no fanfare.
Isn't Dart a compiled language that can be compiled to JS via dart2js and not "on top of JavaScript"?