fix: Fix init segment equality in Segment Prefetch (#6537)

lib/media/segment_prefetch.js

@@ -147,7 +147,12 @@ shaka.media.SegmentPrefetch = class {
     }
 
     // init segments are ignored from the prefetch limit
-    if (!this.initSegmentPrefetchMap_.has(initSegmentReference)) {
+    const initSegments = Array.from(this.initSegmentPrefetchMap_.keys());
+    const someReference = initSegments.some((reference) => {
+      return shaka.media.InitSegmentReference.equal(
+          reference, initSegmentReference);
+    });
+    if (!someReference) {
       const segmentPrefetchOperation =
         new shaka.media.SegmentPrefetchOperation(this.fetchDispatcher_);
       segmentPrefetchOperation.dispatchFetch(
@@ -270,9 +275,11 @@ shaka.media.SegmentPrefetch = class {
     const segmentReferences = Array.from(this.segmentPrefetchMap_.keys());
     for (const initSegmentReference of this.initSegmentPrefetchMap_.keys()) {
       // if no segment references this init segment, we should remove it.
-      if (!segmentReferences.some(
-          (segmentReference) =>
-            segmentReference.initSegmentReference === initSegmentReference)) {
+      const someReference = segmentReferences.some((segmentReference) => {
+        return shaka.media.InitSegmentReference.equal(
+            segmentReference.initSegmentReference, initSegmentReference);
+      });
+      if (!someReference) {
         this.abortPrefetchedSegment_(initSegmentReference);
       }
     }