[video-raf] Enable video-raf by default

This CL turns on HTMLVideoElement.requestAnimationFrame() by default.

Spec: https://wicg.github.io/video-raf/
Blink-dev intent-to-ship: https://wicg.github.io/video-raf/
WPT: https://wpt.fyi/results/video-raf

Bug: 1012063
Change-Id: I5f44a430078e8272d2f9ebb1482e11e936697fb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2101242
Commit-Queue: Thomas Guilbert <tguilbert@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Auto-Submit: Thomas Guilbert <tguilbert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749965}

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1759,7 +1759,7 @@
     {
       // See https://crbug.com/1012063
       name: "VideoRequestAnimationFrame",
-      status: "experimental",
+      status: "stable",
     },
     {
       name: "VideoRotateToFullscreen",

third_party/blink/web_tests/virtual/stable/webexposed/element-instance-property-listing-expected.txt

@@ -1100,6 +1100,7 @@ html element video
     property autoplay
     property buffered
     property canPlayType
+    property cancelAnimationFrame
     property captureStream
     property controls
     property controlsList
@@ -1134,6 +1135,7 @@ html element video
     property preload
     property readyState
     property remote
+    property requestAnimationFrame
     property requestPictureInPicture
     property seekable
     property seeking

third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt

@@ -3685,8 +3685,10 @@ interface HTMLVideoElement : HTMLMediaElement
     getter webkitDroppedFrameCount
     getter webkitSupportsFullscreen
     getter width
+    method cancelAnimationFrame
     method constructor
     method getVideoPlaybackQuality
+    method requestAnimationFrame
     method requestPictureInPicture
     method webkitEnterFullScreen
     method webkitEnterFullscreen