Fix video seeking.

Regression was introduced in d0e854e9d8.

Each time you hide() a widget its mousePress state is reset and
mouseMoveEvent() / mouseReleaseEvent() handlers are never called.

So you can't toggle (hide + show) widgets that are mouse-pressed.

Fixes #4802.

Telegram/SourceFiles/mediaview.cpp

@@ -2961,9 +2961,6 @@ bool MediaView::eventFilter(QObject *obj, QEvent *e) {
 				activate = true;
 			}
 			if (activate) {
-				if (_controlsState == ControlsHiding || _controlsState == ControlsHidden) {
-					int a = 0;
-				}
 				activateControls();
 			}
 		}