Disable v8.browsing_desktop/flipboard on Linux

The test has recently become much flakier.

TBR=nednguyen@chromium.org
CC=mythria@chromium.org,ulan@chromium.org
NOTRY=true

Bug: 864718
Change-Id: Ief78f4e4525bb562416bfb293770ed0b905dc32c
Reviewed-on: https://chromium-review.googlesource.com/1141067Reviewed-by: Charlie Andrews <charliea@chromium.org>
Commit-Queue: Charlie Andrews <charliea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575765}

tools/perf/expectations.config

@@ -342,6 +342,7 @@ crbug.com/813165 [ Win ] v8.browsing_desktop/browse:media:flickr_infinite_scroll
 crbug.com/805934 [ Mac_10.12 ] v8.browsing_desktop/browse:tech:discourse_infinite_scroll [ Skip ]
 crbug.com/839470 [ Win ] v8.browsing_desktop/browse:social:twitter_infinite_scroll [ Skip ]
 crbug.com/854239 [ Linux ] v8.browsing_desktop/browse:social:twitter_infinite_scroll [ Skip ]
+crbug.com/864718 [ Linux ] v8.browsing_desktop/browse:news:flipboard [ Skip ]
 
 # Benchmark: v8.browsing_desktop-future
 crbug.com/773084 [ Mac ] v8.browsing_desktop-future/browse:tools:maps [ Skip ]