The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/be588ee822c6561bc56e68686fc16fd6008770d3

commit be588ee822c6561bc56e68686fc16fd6008770d3
Author: Fredrik Söderquist <fs@opera.com>
Date: Sat Nov 11 17:35:16 2017

Make TextTrackCue::CueDidChange ordering updates fine-grained

Only do an remove-add cycle for the cue when the start or end time is
updated. This will avoid changing the cue order for cues which need to
make use of the "tie-breaker" (have same 'startTime' and 'endTime'.)
It should also make non-time updates to a cue faster.

Remove media/track/opera/interfaces/VTTCue/snapToLines.html since it's
a duplicate of the WPT test.

Bug:  783779 
Change-Id: I919b0acdb6ec2e6f0b6e11fb75996e7292168f95
Reviewed-on: https://chromium-review.googlesource.com/763527
Reviewed-by: srirama chandra sekhar <srirama.m@samsung.com>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#515845}
[delete] https://crrev.com/9fcebbe1b25bd4ac2a51aef552e43f15f7850817/third_party/WebKit/LayoutTests/external/wpt/webvtt/api/VTTCue/snapToLines-expected.txt
[delete] https://crrev.com/9fcebbe1b25bd4ac2a51aef552e43f15f7850817/third_party/WebKit/LayoutTests/media/track/opera/interfaces/VTTCue/snapToLines-expected.txt
[delete] https://crrev.com/9fcebbe1b25bd4ac2a51aef552e43f15f7850817/third_party/WebKit/LayoutTests/media/track/opera/interfaces/VTTCue/snapToLines.html
[modify] https://crrev.com/be588ee822c6561bc56e68686fc16fd6008770d3/third_party/WebKit/Source/core/html/track/TextTrack.cpp
[modify] https://crrev.com/be588ee822c6561bc56e68686fc16fd6008770d3/third_party/WebKit/Source/core/html/track/TextTrack.h
[modify] https://crrev.com/be588ee822c6561bc56e68686fc16fd6008770d3/third_party/WebKit/Source/core/html/track/TextTrackCue.cpp
[modify] https://crrev.com/be588ee822c6561bc56e68686fc16fd6008770d3/third_party/WebKit/Source/core/html/track/TextTrackCue.h
[modify] https://crrev.com/be588ee822c6561bc56e68686fc16fd6008770d3/third_party/WebKit/Source/core/html/track/vtt/VTTCue.cpp
[modify] https://crrev.com/be588ee822c6561bc56e68686fc16fd6008770d3/third_party/WebKit/Source/core/html/track/vtt/VTTCue.h