refator(video): guarantee connectStreams scope is valid

The original debounce implementation (lodash) preserved the
caller's context - radash didn't, so it was failing and it wasn't noticed.

The new debounce implementation with the native function seems to preserve caller's context, but as a safety measure this commit binds the method to its appropriate scope.

bigbluebutton-html5/imports/ui/components/video-provider/component.jsx

@@ -175,6 +175,7 @@ class VideoProvider extends Component {
     this.onWsClose = this.onWsClose.bind(this);
     this.onWsMessage = this.onWsMessage.bind(this);
     this.updateStreams = this.updateStreams.bind(this);
+    this.connectStreams = this.connectStreams.bind(this);
     this.debouncedConnectStreams = debounce(
       this.connectStreams,
       VideoService.getPageChangeDebounceTime(),