rollback updateDimensions to counting video elements instead of peers(needed fixes screensharing)

app/lib/components/Peers.jsx

@@ -22,7 +22,12 @@ class Peers extends React.Component
 
 	updateDimensions = () =>
 	{
-		const n = this.props.peers.length;
+		const n = this.props.videoStreams ? this.props.videoStreams : 0;
+
+		if (n == 0)
+		{
+			return;
+		}
 
 		const width = this.refs.peers.clientWidth;
 		const height = this.refs.peers.clientHeight;