Disable failing blink_perf.layout test on Android

TBR=nednguyen@chromium.org
NOTRY=true

Bug: 832686
Change-Id: Ia03388a34d307ddea50cd8158a4e09a2243dfe6e
Reviewed-on: https://chromium-review.googlesource.com/1012483Reviewed-by: Charlie Andrews <charliea@chromium.org>
Commit-Queue: Charlie Andrews <charliea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550678}

tools/perf/expectations.config

@@ -30,6 +30,8 @@ crbug.com/799184 [ Android_One ] blink_perf.events/EventsDispatchingInShadowTree
 
 # Benchmark: blink_perf.layout
 crbug.com/551950 [ Android_Svelte ] blink_perf.layout/* [ Skip ]
+crbug.com/832686 [ Nexus_5 ] blink_perf.layout/subtree-detaching.html [ Skip ]
+crbug.com/832686 [ Nexus_7 ] blink_perf.layout/subtree-detaching.html [ Skip ]
 
 # Benchmark: blink_perf.paint
 crbug.com/574483 [ Android_Svelte ] blink_perf.paint/* [ Skip ]