Implement JsContainerFromValue for StructureSpawn

(needed for the changes in the starter I pushed a couple days ago for the starter but didn't commit)

src/objects/impls/structure_spawn.rs

@@ -1,6 +1,6 @@
-use crate::{Part, constants::ReturnCode, objects::{Creep, OwnedStructure, RoomObject, Store, Structure}, prelude::*};
+use crate::{Part, constants::ReturnCode, objects::{Creep, OwnedStructure, RoomObject, Store, Structure}, prelude::*, containers::JsContainerFromValue};
 use js_sys::{Array, JsString, Object};
-use wasm_bindgen::prelude::*;
+use wasm_bindgen::{JsCast, prelude::*};
 
 #[wasm_bindgen]
 extern "C" {
@@ -84,6 +84,12 @@ impl StructureSpawn {
     }
 }
 
+impl JsContainerFromValue for StructureSpawn {
+    fn from_value(val: JsValue) -> Self {
+        val.unchecked_into()
+    }
+}
+
 impl HasStore for StructureSpawn {
     fn store(&self) -> Store {
         Self::store(self)