fix(browser): send key events to web view's focus proxy

Fixes regression introduced by migration to Qt WebEngine,
which caused search toolbar not to propagate navigation keys
to the web view.

Related to #703.

src/libs/browser/searchtoolbar.cpp

@@ -137,7 +137,7 @@ bool SearchToolBar::eventFilter(QObject *object, QEvent *event)
         case Qt::Key_Up:
         case Qt::Key_PageDown:
         case Qt::Key_PageUp:
-            QCoreApplication::sendEvent(m_webView, event);
+            QCoreApplication::sendEvent(m_webView->focusProxy(), event);
             return true;
         default:
             break;