UI/AppKit: Implement exiting fullscreen

UI/AppKit/Interface/LadybirdWebView.h

@@ -56,6 +56,7 @@
 - (void)handleResize;
 - (void)handleDevicePixelRatioChange;
 - (void)handleDisplayRefreshRateChange;
+- (void)handleExitFullScreen;
 - (void)handleVisibility:(BOOL)is_visible;
 
 - (void)findInPage:(NSString*)query

UI/AppKit/Interface/LadybirdWebView.mm

@@ -192,6 +192,11 @@ struct HideCursor {
     m_web_view_bridge->set_maximum_frames_per_second([[[self window] screen] maximumFramesPerSecond]);
 }
 
+- (void)handleExitFullScreen
+{
+    m_web_view_bridge->exit_fullscreen();
+}
+
 - (void)handleVisibility:(BOOL)is_visible
 {
     m_web_view_bridge->set_system_visibility_state(is_visible
@@ -843,6 +848,19 @@ struct HideCursor {
         m_web_view_bridge->did_update_window_rect();
     };
 
+    m_web_view_bridge->on_exit_fullscreen_window = [weak_self]() {
+        LadybirdWebView* self = weak_self;
+        if (self == nil) {
+            return;
+        }
+
+        if (([[self window] styleMask] & NSWindowStyleMaskFullScreen) != 0) {
+            [[self window] toggleFullScreen:nil];
+        }
+
+        m_web_view_bridge->did_update_window_rect();
+    };
+
     m_web_view_bridge->on_theme_color_change = [weak_self](auto color) {
         LadybirdWebView* self = weak_self;
         if (self == nil) {

UI/AppKit/Interface/LadybirdWebViewBridge.cpp

@@ -59,6 +59,11 @@ void WebViewBridge::set_maximum_frames_per_second(u64 maximum_frames_per_second)
     client().async_set_maximum_frames_per_second(m_client_state.page_index, maximum_frames_per_second);
 }
 
+void WebViewBridge::exit_fullscreen()
+{
+    client().async_exit_fullscreen(m_client_state.page_index);
+}
+
 void WebViewBridge::update_palette()
 {
     auto theme = create_system_palette();

UI/AppKit/Interface/LadybirdWebViewBridge.h

@@ -31,6 +31,8 @@ public:
 
     void set_maximum_frames_per_second(u64 maximum_frames_per_second);
 
+    void exit_fullscreen();
+
     void update_palette();
 
     void enqueue_input_event(Web::MouseEvent);

UI/AppKit/Interface/TabController.mm

@@ -453,6 +453,11 @@ static NSString* const TOOLBAR_TAB_OVERVIEW_IDENTIFIER = @"ToolbarTabOverviewIde
     [[[self tab] web_view] handleDisplayRefreshRateChange];
 }
 
+- (void)windowDidExitFullScreen:(NSNotification*)notification
+{
+    [[[self tab] web_view] handleExitFullScreen];
+}
+
 #pragma mark - NSToolbarDelegate
 
 - (NSToolbarItem*)toolbar:(NSToolbar*)toolbar