Allow trapping Object.getPrototypeOf in a C proxy class

[ruochenjia]

Currently proxy objects created using C code can only trap property access, but not internal object operations like Object.setPrototypeOf, Object.preventExtensions, which a regular proxy handler in JavaScript could do. This makes it more difficult to pass external JS objects into the quickjs VM when running a WASM version of quickjs.

EMSCRIPTEN_KEEPALIVE void* vm_createproxyobject(JSContext* ctx, JSClassExoticMethods* handler) {
	JSClassID id = JS_NewClassID(0);

	// handler->has_property = ...
	// handler->get_property = ...

	JSClassDef def;
	def.exotic = handler;
	def.class_name = "dummy";

	JS_NewClass(JS_GetRuntime(ctx), id, &def);

	return JS_VALUE_GET_PTR(JS_NewObjectClass(ctx, id));
}