Support negative timestamps of TextTrackCue

https://bugs.webkit.org/show_bug.cgi?id=93143
rdar://problem/113035924

Reviewed by Eric Carlson.

This patch aligns WebKit with Blink / Chromium, Gecko / Firefox and Web-Spec.

Merge: https://chromium-review.googlesource.com/c/chromium/src/+/863270

Ensure proper behaviour for negative timestamps of TextTrackCue.
1. Cues with negative startTime should become active from 0s.
2. Cues with negative startTime and endTime should never be active.

Web-Spec References: whatwg/html@af1b8e2 and
https://www.w3.org/Bugs/Public/show_bug.cgi?id=18480

* Source/WebCore/html/track/TextTrack.cpp:
(TextTrack::addCue): Remove 'TODO' and greater then 'zeroTime' case
* Source/WebCore/html/track/TextTrackCue.cpp:
(TextTrackCue::setStartTime): Remove 'TODO' and remove 'value' less than 0 early return case
(TextTrackCue::setEndTime): Ditto
* Source/WebCore/html/track/TextTrackCueList.cpp:
(TextTrackCueList::add): Remove 'ASSERT' for 'non-negative' case
* LayoutTests/imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-cue-negative-timestamp-events-expected.txt: Rebaselined
* LayoutTests/imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-cue-negative-duration-expected.txt: Rebaselined
* LayoutTests/media/track/track-cue-negative-timestamp.html: Removed in favor of WPT
* LayoutTests/media/track/track-cue-negative-timestamp-expected.txt: Ditto

Canonical link: https://commits.webkit.org/267042@main

LayoutTests/imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-cue-negative-duration-expected.txt

@@ -1,4 +1,4 @@
 
 
-FAIL Enter, Exit events for a cue with negative duration assert_equals: expected 1 but got 0
+PASS Enter, Exit events for a cue with negative duration
 

LayoutTests/imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-cue-negative-timestamp-events-expected.txt

@@ -1,4 +1,4 @@
 
 
-FAIL Enter, Exit events for cues with negative timestamps assert_equals: expected 1 but got 0
+PASS Enter, Exit events for cues with negative timestamps
 

Source/WebCore/html/track/TextTrack.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011, 2013 Google Inc. All rights reserved.
+ * Copyright (C) 2011-2018 Google Inc. All rights reserved.
  * Copyright (C) 2011-2021 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -327,8 +327,7 @@ ExceptionOr<void> TextTrack::addCue(Ref<TextTrackCue>&& cue)
 
     INFO_LOG(LOGIDENTIFIER, cue.get());
 
-    // TODO(93143): Add spec-compliant behavior for negative time values.
-    if (!cue->startMediaTime().isValid() || !cue->endMediaTime().isValid() || cue->startMediaTime() < MediaTime::zeroTime() || cue->endMediaTime() < MediaTime::zeroTime())
+    if (!cue->startMediaTime().isValid() || !cue->endMediaTime().isValid())
         return { };
 
     // 4.8.10.12.5 Text track API

Source/WebCore/html/track/TextTrackCue.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011, 2013 Google Inc.  All rights reserved.
+ * Copyright (C) 2011-2018 Google Inc.  All rights reserved.
  * Copyright (C) 2011-2020 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -279,8 +279,7 @@ void TextTrackCue::setId(const AtomString& id)
 
 void TextTrackCue::setStartTime(double value)
 {
-    // TODO(93143): Add spec-compliant behavior for negative time values.
-    if (m_startTime.toDouble() == value || value < 0)
+    if (m_startTime.toDouble() == value)
         return;
 
     setStartTime(MediaTime::createWithDouble(value));
@@ -295,8 +294,7 @@ void TextTrackCue::setStartTime(const MediaTime& value)
 
 void TextTrackCue::setEndTime(double value)
 {
-    // TODO(93143): Add spec-compliant behavior for negative time values.
-    if (m_endTime.toDouble() == value || value < 0)
+    if (m_endTime.toDouble() == value)
         return;
 
     setEndTime(MediaTime::createWithDouble(value));

Source/WebCore/html/track/TextTrackCueList.cpp

@@ -97,8 +97,6 @@ TextTrackCueList& TextTrackCueList::activeCues()
 void TextTrackCueList::add(Ref<TextTrackCue>&& cue)
 {
     ASSERT(!m_vector.contains(cue.ptr()));
-    ASSERT(cue->startMediaTime() >= MediaTime::zeroTime());
-    ASSERT(cue->endMediaTime() >= MediaTime::zeroTime());
 
     RefPtr<TextTrackCue> cueRefPtr { WTFMove(cue) };
     unsigned insertionPosition = std::upper_bound(m_vector.begin(), m_vector.end(), cueRefPtr, cueSortsBefore) - m_vector.begin();