zlacker

Though the fact that the code is so incoherent and inconsistent plausibly makes it more impressive that they still managed to make something that works at all, and weakens the argument that "all they did was copy/translate some existing other things to Rust."

That said, it's possible that none of that code even gets executed at run time, and the only code that is actually run is some translated glue code, with the other million lines essentially dead, so who knows.

>>daxfoh+(OP)
I don't think it's all copy/pasted; it is quite an original byzantine architecture.

You're right that lots of code appears only used in unit-tests, of which there is an enormous amount(making it hard to tell whether what is being tested makes sense). In Servo we don't have a single line of unit-tests in the script component, because all of it is covered by the WPT integration test suite shared with all other engines...