Enable the flag; Call capture event listeners in capturing phase at shadow hosts

This CL is a follow-up for https://chromium-review.googlesource.com/c/chromium/src/+/1212255.

It looks WebKit also landed the CL: https://trac.webkit.org/changeset/236002/webkit.

fast/dom/shadow/shadow-boundary-events.html is the only existing test which needs the rebase.

BUG=883650

Change-Id: Iecee6777a207b956b1dad6cc842061fd460ec6ab
Reviewed-on: https://chromium-review.googlesource.com/1229741Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592255}

third_party/WebKit/LayoutTests/TestExpectations

@@ -1966,7 +1966,6 @@ crbug.com/404597 fast/forms/long-text-in-input.html [ Skip ]
 # Web Components related tests (Shadow DOM, Custom Elements) failures.
 crbug.com/392771 external/wpt/shadow-dom/untriaged/styles/test-003.html [ Failure ]
 crbug.com/869308 shadow-dom/imperative-api.html [ Failure ]
-crbug.com/883650 external/wpt/shadow-dom/event-dispatch-order.tentative.html [ Failure ]
 
 crbug.com/552494 virtual/prefer_compositing_to_lcd_text/scrollbars/overflow-scrollbar-combinations.html [ Pass Failure ]
 

third_party/WebKit/LayoutTests/fast/dom/shadow/shadow-boundary-events-expected.txt

@@ -77,8 +77,8 @@ PASS dispatchedEvent("blur") is ["divB(<-divC)(@divA)(capturing phase)", "divB(<
 
 Old focused node and new focused node exist in separated subtrees, crossing shadow boundaries. Making sure that an event is not dispatched beyond the lowest common boundary.
 Moving focus from shadowD/shadowF/shadowG/divH to shadowD/shadowK/divL
-PASS dispatchedEvent("focus") is ["shadowK(<-shadowF)(@divJ)(capturing phase)", "divL(<-shadowF)(@divL)", "shadowK(<-shadowF)(@shadowK)"]
-PASS dispatchedEvent("blur") is ["shadowF(<-shadowK)(@divE)(capturing phase)", "divH(<-shadowK)(@divH)", "shadowG(<-shadowK)(@shadowG)", "shadowF(<-shadowK)(@shadowF)"]
+PASS dispatchedEvent("focus") is ["shadowK(<-shadowF)(@divJ)(capturing phase)", "shadowK(<-shadowF)(@shadowK)", "divL(<-shadowF)(@divL)"]
+PASS dispatchedEvent("blur") is ["shadowF(<-shadowK)(@divE)(capturing phase)", "shadowF(<-shadowK)(@shadowF)", "shadowG(<-shadowK)(@shadowG)", "divH(<-shadowK)(@divH)"]
 PASS successfullyParsed is true
 
 TEST COMPLETE

third_party/WebKit/LayoutTests/fast/dom/shadow/shadow-boundary-events.html

@@ -197,8 +197,8 @@ function test()
 
     moveFocus('shadowD/shadowF/shadowG/divH', 'shadowD/shadowK/divL',
               'Old focused node and new focused node exist in separated subtrees, crossing shadow boundaries. Making sure that an event is not dispatched beyond the lowest common boundary.');
-    shouldBe('dispatchedEvent("focus")', '["shadowK(<-shadowF)(@divJ)(capturing phase)", "divL(<-shadowF)(@divL)", "shadowK(<-shadowF)(@shadowK)"]');
-    shouldBe('dispatchedEvent("blur")', '["shadowF(<-shadowK)(@divE)(capturing phase)", "divH(<-shadowK)(@divH)", "shadowG(<-shadowK)(@shadowG)", "shadowF(<-shadowK)(@shadowF)"]');
+    shouldBe('dispatchedEvent("focus")', '["shadowK(<-shadowF)(@divJ)(capturing phase)", "shadowK(<-shadowF)(@shadowK)", "divL(<-shadowF)(@divL)"]');
+    shouldBe('dispatchedEvent("blur")', '["shadowF(<-shadowK)(@divE)(capturing phase)", "shadowF(<-shadowK)(@shadowF)", "shadowG(<-shadowK)(@shadowG)", "divH(<-shadowK)(@divH)"]');
 }
 
 test();

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -159,6 +159,7 @@
     },
     {
       name: "CallCaptureListenersAtCapturePhaseAtShadowHosts",
+      status: "stable",
     },
     {
       name: "Canvas2dContextLostRestored",