Revert "Reapply zone tasks."

tests/html/html.status

Index: tests/html/html.status
diff --git a/tests/html/html.status b/tests/html/html.status
index da27d619585a5d083e25b3cba67962c122cd14bc..79f1d469e08b7a80a22561171992eee2b95c5aab 100644
--- a/tests/html/html.status
+++ b/tests/html/html.status
@@ -145,7 +145,6 @@ notification_test/supported_notification: Fail # Notification not supported on I
 event_test: RuntimeError # Issue 23437. Only three failures, but hard to break them out.
 wheelevent_test: RuntimeError # Issue 23437
 text_event_test: RuntimeError # Issue 23437
-event_zone_task_test: RuntimeError # Issue 23437
 transition_event_test/functional: Skip # Times out. Issue 22167
 request_animation_frame_test: Skip # Times out. Issue 22167
 
@@ -189,7 +188,6 @@ touchevent_test/supported: Fail # IE does not support TouchEvents
 webgl_1_test/supported: Fail
 websql_test/supported: Fail
 xhr_test/json: Fail # IE10 returns string, not JSON object
-xhr_task_test/json: Fail # IE10 returns string, not JSON object
 xhr_test/supported_overrideMimeType: Fail
 xsltprocessor_test/supported: Fail
 worker_test/functional: Fail # IE uses incorrect security context for Blob URIs.
@@ -247,8 +245,7 @@ svgelement_test/supported_set: Fail
 touchevent_test/supported: Fail # IE does not support TouchEvents
 webgl_1_test/functional: Fail
 websql_test/supported: Fail
-xhr_test/json: Fail # IE11 returns string, not JSON object
-xhr_task_test/json: Fail # IE11 returns string, not JSON object
+xhr_test/json: Fail # IE10 returns string, not JSON object
 xsltprocessor_test/supported: Fail
 
 [ $runtime == ie10 ]
@@ -378,7 +375,6 @@ touchevent_test/supported: Fail
 
 [ (($runtime == dartium || $runtime == drt) && $system == macos) || $system == windows ]
 xhr_test/xhr: Skip # Times out.  Issue 21527
-xhr_task_test/xhr: Skip # Times out.  Issue 21527
 
 [ $compiler == dart2analyzer ]
 custom/document_register_basic_test: StaticWarning