Break out a separate mute modal with a hide-notifications checkbox.

app/javascript/mastodon/reducers/mutes.js

@@ -0,0 +1,29 @@
+import Immutable from 'immutable';
+
+import {
+	MUTES_INIT_MODAL,
+	MUTES_TOGGLE_HIDE_NOTIFICATIONS,
+} from '../actions/mutes';
+
+const initialState = Immutable.Map({
+	new: Immutable.Map({
+		isSubmitting: false,
+		account: null,
+		notifications: true,
+	}),
+});
+
+export default function mutes(state = initialState, action) {
+	switch (action.type) {
+	case MUTES_INIT_MODAL:
+		return state.withMutations((state) => {
+			state.setIn(['new', 'isSubmitting'], false);
+			state.setIn(['new', 'account'], action.account);
+			state.setIn(['new', 'notifications'], true);
+		});
+	case MUTES_TOGGLE_HIDE_NOTIFICATIONS:
+		return state.setIn(['new', 'notifications'], !state.getIn(['new', 'notifications']));
+	default:
+		return state;
+	}
+}