MediaTime::invalidTime() isn't convertible without loss into CMTime

[Jean-Yves Avenard [:jya]]

Consider the following code:
```
        auto invalid = MediaTime::invalidTime();
        auto cminvalid = PAL::toCMTime(invalid);
        auto invalid2 = PAL::toMediaTime(cminvalid);
        ASSERT(invalid == invalid2);
```

the assertion will fail.

The reason is that PAL::toCMTime(MediaTime::invalidTime()) will generate a CMTime that has the flag kCMTimeFlags_HasBeenRounded set.

This causes failure here 
https://webkit-search.igalia.com/webkit/rev/ceb5e25a803df6cd6ea1c45859e4e03bbf659f75/Source/WebKit/Shared/mac/MediaFormatReader/MediaSampleByteRange.cpp#49

[Jean-Yves Avenard [:jya]]

Actually, earlier description is incorrect:

the code of toCMTime is as follow:
```
    CMTime time;

    if (mediaTime.hasDoubleValue())
        time = CMTimeMakeWithSeconds(mediaTime.toDouble(), mediaTime.timeScale());
    else
        time = CMTimeMake(mediaTime.timeValue(), mediaTime.timeScale());

    if (mediaTime.isValid())
        time.flags |= kCMTimeFlags_Valid;
    if (mediaTime.hasBeenRounded())
        time.flags |= kCMTimeFlags_HasBeenRounded;
    if (mediaTime.isPositiveInfinite())
        time.flags |= kCMTimeFlags_PositiveInfinity;
    if (mediaTime.isNegativeInfinite())
        time.flags |= kCMTimeFlags_NegativeInfinity;

    return time;
```

what converting MediaTime::invalidTime() : `CMTimeMake(mediaTime.timeValue(), mediaTime.timeScale());` will return a valid time and that flag isn't reset.

[Radar WebKit Bug Importer]

<rdar://problem/89814921>

[Jean-Yves Avenard [:jya]]

Created attachment 453845 [details]
Patch

[Jean-Yves Avenard [:jya]]

Created attachment 453886 [details]
Patch

[Jean-Yves Avenard [:jya]]

Created attachment 453887 [details]
Patch

[Jean-Yves Avenard [:jya]]

Created attachment 453888 [details]
Patch

Fix iOS compilation

[Jer Noble]

Comment on attachment 453888 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=453888&action=review

> Source/WebCore/PAL/ChangeLog:15
> [phone]  Jean-Yves Avenard  <[e-mail]>

Nit: This ChangeLog entry should get merged with the one above it.

[Jean-Yves Avenard [:jya]]

Created attachment 454028 [details]
Patch

[Jean-Yves Avenard [:jya]]

Created attachment 454031 [details]
Patch

[EWS]

Committed r290964 (248144@main): <https://commits.webkit.org/248144@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 454031 [details].