fix: noop vtt segment loader handle data (#959)

We should noop handleData in vtt segment loader so that any captions which we don't support the type of, such as stpp.ttml.im1t from tears of steal widevine unified streaming do not attempt to append to sourceBuffers and cause a player append error.

src/vtt-segment-loader.js

@@ -375,6 +375,10 @@ export default class VTTSegmentLoader extends SegmentLoader {
     this.handleAppendsDone_();
   }
 
+  handleData_() {
+    // noop as we shouldn't be getting video/audio data captions
+    // that we do not support here.
+  }
   updateTimingInfoEnd_() {
     // noop
   }