Restore vanilla components

app/javascript/mastodon/reducers/modal.js

@@ -0,0 +1,17 @@
+import { MODAL_OPEN, MODAL_CLOSE } from '../actions/modal';
+
+const initialState = {
+  modalType: null,
+  modalProps: {},
+};
+
+export default function modal(state = initialState, action) {
+  switch(action.type) {
+  case MODAL_OPEN:
+    return { modalType: action.modalType, modalProps: action.modalProps };
+  case MODAL_CLOSE:
+    return initialState;
+  default:
+    return state;
+  }
+};