Enable growable array buffers

[sbc100]

Currently this is still behind a flag so we never turn it on by default.

Fixes: #24287

[kleisauke]

IIUC, we could also conditionally exclude these two behind GROWABLE_ARRAYBUFFERS:

emscripten/system/lib/standalone/standalone.c

Lines 133 to 136 in 8f12acf

	#if !defined(EMSCRIPTEN_PURE_WASI)
	// Success, update JS (see https://github.com/WebAssembly/WASI/issues/82)
	emscripten_notify_memory_growth(0);
	#endif

emscripten/src/lib/libcore.js

Lines 2418 to 2424 in 8f12acf

	#if PURE_WASI
	// In PURE_WASI mode we can't assume the wasm binary was built by emscripten
	// and politely notify us on memory growth. Instead we have to check for
	// possible memory growth on each syscall.
	var pre = '\nif (!HEAPU8.byteLength) _emscripten_notify_memory_growth(0);\n'
	library[x + '__deps'].push('emscripten_notify_memory_growth');
	#else

[sbc100]

IIUC, we could also conditionally exclude these two behind GROWABLE_ARRAYBUFFERS:

emscripten/system/lib/standalone/standalone.c

Lines 133 to 136 in 8f12acf

	#if !defined(EMSCRIPTEN_PURE_WASI)
	// Success, update JS (see https://github.com/WebAssembly/WASI/issues/82)
	emscripten_notify_memory_growth(0);
	#endif

emscripten/src/lib/libcore.js

Lines 2418 to 2424 in 8f12acf

	#if PURE_WASI
	// In PURE_WASI mode we can't assume the wasm binary was built by emscripten
	// and politely notify us on memory growth. Instead we have to check for
	// possible memory growth on each syscall.
	var pre = '\nif (!HEAPU8.byteLength) _emscripten_notify_memory_growth(0);\n'
	library[x + '__deps'].push('emscripten_notify_memory_growth');
	#else

Yeah.. I thought of doing that, but didn't want to create yet another library variant. But I think it might be worth it.

[sbc100]

Done!

[sbc100]

Added a new test

[RReverser]

Worth appending to v8_args too, like we do for other experimental features?

[sbc100]

Done.

[sbc100]

This change should be good to go now. PTAL

[RReverser]

Nit: I'd keep this inline in the original flags, after all if that warning shows up in "growable array buffer" mode, we also want the test to error out as it would be unexpected.

[RReverser]

Left a nitpick, but otherwise very exciting!