move to api crate

xr_api/src/backend/webxr/utils.rs

@@ -0,0 +1,17 @@
+use wasm_bindgen::JsValue;
+use wasm_bindgen_futures::JsFuture;
+use web_sys::js_sys::Promise;
+
+pub trait PromiseRes {
+    fn resolve<T: From<JsValue>>(self) -> Result<T, JsValue>;
+}
+
+impl PromiseRes for Promise {
+    fn resolve<T: From<JsValue>>(self) -> Result<T, JsValue> {
+        resolve_promise(self)
+    }
+}
+
+pub fn resolve_promise<T: From<JsValue>>(promise: Promise) -> Result<T, JsValue> {
+    futures::executor::block_on(async move { JsFuture::from(promise).await.map(Into::into) })
+}