LibGUI: Invalidate IconView cache on font change

Changing the font means we have to recalculate all the item rects etc.

Userland/Libraries/LibGUI/IconView.cpp

@@ -59,6 +59,12 @@ void IconView::resize_event(ResizeEvent& event)
     }
 }
 
+void IconView::did_change_font()
+{
+    AbstractView::did_change_font();
+    rebuild_item_cache();
+}
+
 void IconView::rebuild_item_cache() const
 {
     auto prev_item_count = m_item_data_cache.size();

Userland/Libraries/LibGUI/IconView.h

@@ -46,6 +46,9 @@ public:
 
     virtual void select_all() override;
 
+protected:
+    virtual void did_change_font() override;
+
 private:
     IconView();