Fix bug where vector freezes on power level event

Make rate_limited_function accept functions with args so we can just ratelimit the event handler & be done with it.

Fixes https://github.com/vector-im/vector-web/issues/1877

src/components/structures/RoomView.js

@@ -482,7 +482,9 @@ module.exports = React.createClass({
         }
     },
 
-    onRoomStateMember: function(ev, state, member) {
+    // rate limited because a power level change will emit an event for every
+    // member in the room.
+    onRoomStateMember: new rate_limited_func(function(ev, state, member) {
         // ignore if we don't have a room yet
         if (!this.state.room) {
             return;
@@ -511,7 +513,7 @@ module.exports = React.createClass({
             member.userId === this.props.ConferenceHandler.getConferenceUserIdForRoom(member.roomId)) {
             this._updateConfCallNotification();
         }
-    },
+    }, 500),
 
     _hasUnsentMessages: function(room) {
         return this._getUnsentMessages(room).length > 0;

src/ratelimitedfunc.js

@@ -23,13 +23,13 @@ module.exports = function(f, minIntervalMs) {
         var now = Date.now();
 
         if (self.lastCall < now - minIntervalMs) {
-            f.apply(this);
+            f.apply(this, arguments);
             self.lastCall = now;
         } else if (self.scheduledCall === undefined) {
             self.scheduledCall = setTimeout(
                 () => {
                     self.scheduledCall = undefined;
-                    f.apply(this);
+                    f.apply(this, arguments);
                     self.lastCall = now;
                 },
                 (self.lastCall + minIntervalMs) - now