Disable flaky SystemHealthBenchmarkSmokeTests.

BUG=836406,836407
TBR=nednguyen@google.com

Change-Id: I477b4acd6502dc034e36f9bca12b7eb9ef1f3fbc
Reviewed-on: https://chromium-review.googlesource.com/1026694
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553412}

tools/perf/expectations.config

@@ -293,6 +293,8 @@ crbug.com/664661 [ Mac ] system_health.memory_desktop/load:games:miniclip [ Skip
 crbug.com/728464 [ All ] system_health.memory_desktop/browse:social:twitter_infinite_scroll [ Skip ]
 crbug.com/799106 [ Win ] system_health.memory_desktop/browse:media:flickr_infinite_scroll [ Skip ]
 crbug.com/812807 [ Linux ] system_health.memory_desktop/browse:media:tumblr [ Skip ]
+crbug.com/836406 [ Linux ] system_health.memory_desktop/browse:news:flipboard [ Skip ]
+crbug.com/836407 [ Linux ] system_health.memory_desktop/browse:tools:maps [ Skip ]
 
 # Benchmark: system_health.memory_mobile
 crbug.com/787001 [ Android_Webview ] system_health.memory_mobile/load:media:soundcloud [ Skip ]