Fullscreen doesn't work on chrome and safari on the Mac

Please include the following in your bug report:

**Version of emscripten/emsdk:**
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 2.0.12

Tested on an Intel Mac with the latest Chrome and Safari.

Attached is the most basic example (which i got from a website to rule out it's my code doing something wrong) which exhibits the exact same behaviour:

- Chrome: if I press the fullscreen button, the whole thing moves to fullscreen but the canvas is invisible. (In my game I do see something still resembling my canvas but it shows random data)
- Safari: It moves to fullscreen and immediately moves back.

Both browsers after exiting fullscreen have the canvas removed from the page. Just the debug block is left.
The html page is the default generated emscripten page.

Attached a zip with an example project with almost nothing going on.

[emscripten_clean_example.zip](https://github.com/emscripten-core/emscripten/files/10134593/emscripten_clean_example.zip)