Right – that's why I didn't say “known compiler and standard library”. That said, it's a difficult comparison because OS updates tend to be more conservative and are definitely less frequent than browser updates, AOT apps in lower-level languages like C/C++ are going to manage a higher percentage of their core data structures because they're pinning something like Boost whereas a JavaScript developer just gets whatever version of Object/Array/etc. is available, and there's not really a concept of a pinned release: if you install Windows apps, you'll pull in major versions of things like .NET or the JVM but there's no analogous practice of pinning a particular browser version. The closest we've come was Internet Explorer's compatibility modes which they've deprecated and which never changed the core JavaScript engine's performance – e.g. IE8-running-as-IE7 still applied the IE8 JavaScript engine's validation and optimizations.