Enable IOv2 by default

Intent to Ship:

https://groups.google.com/a/chromium.org/d/msg/blink-dev/g-pdQdSR0HI/LY6lcGKOCgAJ

Bug: 827639
Change-Id: I4f99a90794badc546bfda7e9af1aeb5d4f0a09bd
Reviewed-on: https://chromium-review.googlesource.com/c/1437497
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626301}

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -643,6 +643,7 @@
     },
     {
       name: "IntersectionObserverV2",
+      status: "stable",
     },
     {
       name: "InvisibleDOM",

third_party/blink/web_tests/TestExpectations

@@ -5418,10 +5418,6 @@ crbug.com/873873 virtual/outofblink-cors/external/wpt/service-workers/service-wo
 crbug.com/873873 virtual/outofblink-cors-ns/external/wpt/service-workers/service-worker/fetch-canvas-tainting-video-cache.https.html [ Timeout Pass ]
 crbug.com/873873 virtual/disabled-service-worker-servicification/external/wpt/service-workers/service-worker/fetch-canvas-tainting-video-cache.https.html [ Timeout Pass ]
 
-# IntersectionObserverV2 tests run in a virtual test suite
-crbug.com/827639 intersection-observer/v2 [ Skip ]
-crbug.com/827639 http/tests/intersection-observer/v2 [ Skip ]
-
 crbug.com/875884 [ Linux ] lifecycle/background-change-lifecycle-count.html [ Pass Failure ]
 crbug.com/875884 [ Win ] lifecycle/background-change-lifecycle-count.html [ Pass Failure ]
 crbug.com/875884 [ Linux ] virtual/threaded/lifecycle/background-change-lifecycle-count.html [ Pass Failure ]

third_party/blink/web_tests/VirtualTestSuites

@@ -741,16 +741,6 @@
     "base": "external/wpt/origin-policy",
     "args": ["--enable-features=OriginPolicy"]
   },
-  {
-    "prefix": "intersection-observer-v2",
-    "base": "intersection-observer/v2",
-    "args": ["--enable-blink-features=IntersectionObserverV2"]
-  },
-  {
-    "prefix": "intersection-observer-v2",
-    "base": "http/tests/intersection-observer/v2",
-    "args": ["--enable-blink-features=IntersectionObserverV2"]
-  },
   {
     "prefix" : "lazyload-policy",
     "base": "external/wpt/feature-policy/experimental-features/lazyload",

third_party/blink/web_tests/virtual/intersection-observer-v2/http/tests/intersection-observer/v2/README.txt

-This is for testing IntersectionObserverV2 -- now with occlusion detection!

third_party/blink/web_tests/virtual/intersection-observer-v2/intersection-observer/v2/README.txt

-This is for testing IntersectionObserverV2 -- now with occlusion detection!

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

@@ -3603,9 +3603,11 @@ interface InputEvent : UIEvent
     method getTargetRanges
 interface IntersectionObserver
     attribute @@toStringTag
+    getter delay
     getter root
     getter rootMargin
     getter thresholds
+    getter trackVisibility
     method constructor
     method disconnect
     method observe
@@ -3617,6 +3619,7 @@ interface IntersectionObserverEntry
     getter intersectionRatio
     getter intersectionRect
     getter isIntersecting
+    getter isVisible
     getter rootBounds
     getter target
     getter time

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

@@ -4214,9 +4214,11 @@ interface InputEvent : UIEvent
     method getTargetRanges
 interface IntersectionObserver
     attribute @@toStringTag
+    getter delay
     getter root
     getter rootMargin
     getter thresholds
+    getter trackVisibility
     method constructor
     method disconnect
     method observe
@@ -4228,6 +4230,7 @@ interface IntersectionObserverEntry
     getter intersectionRatio
     getter intersectionRect
     getter isIntersecting
+    getter isVisible
     getter rootBounds
     getter target
     getter time