fix: Fix end-of-stream detection for VOD

PR #8603 refactored the conditions for being "buffered to the end".
Two of these conditions from Player didn't fit in the new location
(Playhead).  One (this.isEnded()) was moved, and the other
(this.mediaSourceEngine_.ended()) was dropped by accident.  This
restores the dropped condition inside isEnded().

Verified on Chromecast.

Author: joeyparrish

lib/player.js

@@ -9347,6 +9347,13 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     if (!this.video_ || this.video_.ended) {
       return true;
     }
+
+    // This means that MediaSource has buffered the final segment in all
+    // SourceBuffers and is no longer accepting additional segments.
+    if (this.mediaSourceEngine_ && this.mediaSourceEngine_.ended()) {
+      return true;
+    }
+
     return this.fullyLoaded_ && !this.isLive() &&
         this.video_.currentTime >= this.seekRange().end;
   }