PlzNavigate: update layout test filter.

third_party/WebKit/LayoutTests/FlagExpectations/enable-browser-side-navigation

 # These tests currently fail when run with --enable-browser-side-navigation
 # See https://crbug.com/576261
 # https://crbug.com/608372: PlzNavigate: support POST navigations
 crbug.com/608372 fast/forms/form-submit-in-submit-event.html [ Failure ]
 crbug.com/608372 fast/forms/submit-to-url-fragment.html [ Failure ]
 crbug.com/608372 fast/forms/xss-auditor-doesnt-crash-on-post-submit.html [ Timeout ]
 crbug.com/608372 fast/loader/form-state-restore-with-frames.html [ Failure ]
 crbug.com/608372 http/tests/history/back-to-post.html [ Timeout ]
 crbug.com/608372 http/tests/navigation/post-goback-same-url.html [ Failure ]
 crbug.com/608372 virtual/stable/http/tests/navigation/post-goback-same-url.html [ Failure ]
@@ skipping 102 matching lines @@
 crbug.com/576271 http/tests/security/upgrade-insecure-requests/https-header-top-level.html [ Skip ]
 crbug.com/576271 http/tests/security/upgrade-insecure-requests/iframe-upgrade.https.html [ Skip ]
 
 # Properly set ZoomLevel (see IFrameZoomBrowsertests*)
 Bug(none) fast/css/preserve-user-specified-zoom-level-on-reload.html [ Failure ]
 
 # https://crbug.com/648600: Don't output 2 blank spaces at the end of some layout tests
 crbug.com/648600 fast/overflow/overflow-height-float-not-removed-crash.html [ Failure ]
 crbug.com/648600 virtual/spv2/fast/overflow/overflow-height-float-not-removed-crash.html [ Failure ]
 
-# https://crbug.com/648608: Send the right cookies when loading a popup
+# https://crbug.com/648608: Properly set the initator of the navigation.
 crbug.com/648608 http/tests/cookies/same-site/popup-same-site-post.html [ Failure ]
 crbug.com/648608 http/tests/cookies/same-site/popup-same-site.html [ Failure ]
 
 # Untriaged navigation
 Bug(none) fast/dom/Document/open-with-pending-load.html [ Failure ]
 Bug(none) fast/dom/HTMLAnchorElement/anchor-no-multiple-windows.html [ Failure ]
 Bug(none) http/tests/loading/pdf-commit-load-callbacks.html [ Crash ]
 Bug(none) http/tests/navigation/forward-to-fragment-fires-onload.html [ Timeout ]
 Bug(none) http/tests/navigation/response204.html [ Timeout ]
 Bug(none) http/tests/security/cross-frame-access-parent-isolated-world.html [ Timeout ]
@@ skipping 14 matching lines @@
 
 # https://crbug.com/440463: Make ServiceWorker and PlzNavigate play well
 # together.
 Bug(none) http/tests/inspector/network/network-datareceived.html [ Failure ]
 Bug(none) http/tests/inspector/service-workers/service-worker-agents.html [ Failure ]
 Bug(none) http/tests/inspector/service-workers/service-worker-manager.html [ Timeout ]
 Bug(none) http/tests/inspector/service-workers/service-workers-redundant.html [ Timeout ]
 Bug(none) http/tests/inspector/service-workers/user-agent-override.html [ Failure ]
 Bug(none) http/tests/serviceworker/appcache-ordering-main.html [ Failure ]
 Bug(none) http/tests/serviceworker/chromium/sandboxed-iframe-navigator-serviceworker.html [ Failure ]