[MSE] SourceBuffer.buffered should return the same object if it's not modified

• Component: Media
• Status: RESOLVED FIXED

[Jean-Yves Avenard [:jya]]

Per spec, https://w3c.github.io/media-source/#dom-sourcebuffer-buffered

Step 5,
```
5. If intersection ranges does not contain the exact same range information as the current value of this attribute, then update the current value of this attribute to intersection ranges.
6. Return the current value of this attribute.
```

The current value of this attribute should only be modified if it has changed.

However, currently a copy of the attribute is always returned:
https://searchfox.org/wubkat/rev/7a7d33c945c423639d0e625352d98c40411716f2/Source/WebCore/Modules/mediasource/SourceBuffer.cpp#123-124

```
   // 2. Return a new static normalized TimeRanges object for the media segments buffered.
    return m_private->buffered()->copy();
```

seems to be based on an old spec.

[Radar WebKit Bug Importer]

<rdar://problem/106695698>

[Jean-Yves Avenard [:jya]]

Origin of change in the spec was https://www.w3.org/Bugs/Public/show_bug.cgi?id=27790

[Jean-Yves Avenard [:jya]]

Pull request: https://github.com/WebKit/WebKit/pull/11694

[EWS]

Committed 261848@main (f373c652ff7f): <https://commits.webkit.org/261848@main>

Reviewed commits have been landed. Closing PR #11694 and removing active labels.