LibWeb: Implement the HTMLMediaElement fastSeek method

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/32e2207b55
Pull-request: https://github.com/SerenityOS/serenity/pull/18480

Userland/Libraries/LibWeb/HTML/HTMLMediaElement.cpp

@@ -208,6 +208,13 @@ void HTMLMediaElement::set_current_time(double current_time)
     }
 }
 
+// https://html.spec.whatwg.org/multipage/media.html#dom-media-fastseek
+void HTMLMediaElement::fast_seek(double time)
+{
+    // The fastSeek(time) method must seek to the time given by time, with the approximate-for-speed flag set.
+    seek_element(time, MediaSeekMode::ApproximateForSpeed);
+}
+
 // https://html.spec.whatwg.org/multipage/media.html#playing-the-media-resource:current-playback-position-13
 void HTMLMediaElement::set_current_playback_position(double playback_position)
 {

Userland/Libraries/LibWeb/HTML/HTMLMediaElement.h

@@ -66,6 +66,7 @@ public:
 
     double current_time() const;
     void set_current_time(double);
+    void fast_seek(double);
 
     double current_playback_position() const { return m_current_playback_position; }
     void set_current_playback_position(double);

Userland/Libraries/LibWeb/HTML/HTMLMediaElement.idl

@@ -40,6 +40,7 @@ interface HTMLMediaElement : HTMLElement {
 
     // playback state
     attribute double currentTime;
+    undefined fastSeek(double time);
     readonly attribute unrestricted double duration;
     readonly attribute boolean paused;
     readonly attribute boolean ended;