There are still RWX pages in Chrome, something to do with WASM I think. I don’t know about Safari. Old MS Edge used to solve the remapping of the W JIT page to X by moving JITTing to another process and then having it RW in there, but only ever be RX in the primary process.
It doesn't have RWX pages on macOS; macOS on Apple Silicon (and under the Hardened Runtime on Intel, although I'm not sure whether or not Chrome's adopted that) strictly enforces W^X.
