Gardening: FileAPI WPT tests fail in NetworkService.

These were added in r522197 (from r522122) and are failing.

Bug: 777879
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: Ia969cea09329d027b88d6eacbd3c50f322bbe52e
NOTRY: true
TBR: kinuko
Reviewed-on: https://chromium-review.googlesource.com/812586
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522318}

third_party/WebKit/LayoutTests/FlagExpectations/enable-features=NetworkService

@@ -232,3 +232,9 @@ crbug.com/721408 http/tests/inspector-protocol/network/navigation-xfer-size.js [
 
 # Started flaking after test was rewritten in r517585.
 Bug(none) http/tests/devtools/service-workers/service-worker-agents.js [ Crash Pass ]
+
+crbug.com/777879 external/wpt/FileAPI/file/send-file-form-iso-2022-jp.tentative.html [ Crash ]
+crbug.com/777879 external/wpt/FileAPI/file/send-file-form-utf-8.html [ Crash ]
+crbug.com/777879 external/wpt/FileAPI/file/send-file-form-windows-1252.tentative.html [ Crash ]
+crbug.com/777879 external/wpt/FileAPI/file/send-file-form-x-user-defined.tentative.html [ Crash ]
+crbug.com/777879 external/wpt/FileAPI/file/send-file-form.html [ Crash ]