Remove test filter updates after revert of r515816

TBR=xingliu@chromium.org
NOTRY=true

Change-Id: I73c923f8486b611f347e914fe17545175db63970
Reviewed-on: https://chromium-review.googlesource.com/765229Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515887}

testing/buildbot/filters/mojo.fyi.network_browser_tests.filter

@@ -973,10 +973,3 @@
 
 # Started failing after r515789
 -SSLUITestCommittedInterstitials.ProceedLinkOverridable
-
-# TODO(jam): investigate
--SBNavigationObserverBrowserTest.DownloadViaHTML5FileApiWithoutUserGesture
--SBNavigationObserverBrowserTest.DownloadViaHTML5FileApiWithUserGesture
-
-# TODO(xingliu): broke in r515816
--DownloadTest.CloseNewTab4

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

@@ -221,7 +221,3 @@ crbug.com/778721 http/tests/fetch/workers/thorough/redirect-nocors-other-https.h
 crbug.com/778721 http/tests/fetch/workers/thorough/redirect-password-other-https.html [ Pass Failure ]
 crbug.com/778721 http/tests/fetch/workers/thorough/redirect-password.html [ Pass Failure ]
 crbug.com/778721 http/tests/fetch/workers/thorough/scheme-blob.html [ Pass Failure ]
-
-# broke in r515816
-Bug(none) fast/dom/HTMLAnchorElement/anchor-download.html [ Timeout ]
-Bug(none) fast/dom/HTMLAnchorElement/anchor-nodownload-set.html [ Timeout ]