LibWeb: Draw a speaker on media elements to toggle muting audio

Author: https://github.com/trflynn89
Commit: a4cb3b5d4d
Pull-request: https://github.com/SerenityOS/serenity/pull/19409

Userland/Libraries/LibWeb/HTML/HTMLMediaElement.h

@@ -103,6 +103,7 @@ public:
         Optional<CSSPixelRect> control_box_rect;
         Optional<CSSPixelRect> playback_button_rect;
         Optional<CSSPixelRect> timeline_rect;
+        Optional<CSSPixelRect> speaker_button_rect;
     };
     CachedLayoutBoxes& cached_layout_boxes(Badge<Painting::MediaPaintable>) const { return m_layout_boxes; }