serviceworker-notification-properties.html no longer leaks

Fixed by a revert in V8:
https://chromium.googlesource.com/v8/v8/+/9b606523b5e210f60c4260ee5f50a54e8f07adbd

BUG=617137
TBR=jbroman
NOTRY=true

Review-Url: https://codereview.chromium.org/2040153002
Cr-Commit-Position: refs/heads/master@{#398258}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -38,8 +38,6 @@ crbug.com/410974 virtual/scroll_customization/fast/scroll-behavior/scroll-custom
 
 crbug.com/616775 http/tests/inspector-enabled/dedicated-workers-list.html [ Crash ]
 
-crbug.com/617137 http/tests/notifications/serviceworker-notification-properties.html [ Leak ]
-
 # -----------------------------------------------------------------
 # Untriaged but known real leaks.
 # -----------------------------------------------------------------