Disable wikipedia_3g on N6 Webview

TBR=crouleau@chromium.org
CC=kouhei@chromium.org,ksakamoto@chromium.org

Bug: 914100
Change-Id: Ie5bb8c15ea8b8bf8dcc49cd53bd917df7784f30b
Reviewed-on: https://chromium-review.googlesource.com/c/1372727Reviewed-by: Charlie Andrews <charliea@chromium.org>
Commit-Queue: Charlie Andrews <charliea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615766}

tools/perf/expectations.config

@@ -147,6 +147,7 @@ crbug.com/676612 [ Nexus6_Webview ] loading.mobile/GoogleIndonesia_3g [ Skip ]
 crbug.com/676612 [ Nexus6_Webview ] loading.mobile/Kaskus [ Skip ]
 crbug.com/865400 [ Pixel_2 ] loading.mobile/TribunNews_3g [ Skip ]
 crbug.com/865400 [ Pixel_2 ] loading.mobile/Youtube_3g [ Skip ]
+crbug.com/914100 [ Nexus6_Webview ] loading.mobile/Wikipedia_3g [ Skip ]
 
 # Benchmark: memory.long_running_idle_gmail_tbmv2
 crbug.com/611167 [ Android_Svelte ] memory.long_running_idle_gmail_tbmv2/* [ Skip ]