Reenable browse:chrome:newtab on Nexus5

A recent bisect in the linked bug shows that it's passing again.

NOTRY=true
TBR=nednguyen@chromium.org

Bug: 803461
Change-Id: If9e240bbb03a7941ae3fe4ea48149bfe606d9ec4
Reviewed-on: https://chromium-review.googlesource.com/1146772Reviewed-by: Charlie Andrews <charliea@chromium.org>
Commit-Queue: Charlie Andrews <charliea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577173}

tools/perf/expectations.config

@@ -302,7 +302,6 @@ crbug.com/780779 [ Nexus_5 ] system_health.memory_mobile/browse:social:facebook
 crbug.com/738854 [ Nexus_5X ] system_health.memory_mobile/load:tools:drive [ Skip ]
 crbug.com/738854 [ Android_Webview ] system_health.memory_mobile/load:tools:drive [ Skip ]
 crbug.com/797261 [ Android_Webview ] system_health.memory_mobile/load:games:spychase [ Skip ]
-crbug.com/803462 [ Nexus_5 ] system_health.memory_mobile/browse:chrome:newtab [ Skip ]
 crbug.com/834905 [ Nexus_5 ] system_health.memory_mobile/browse:social:pinterest_infinite_scroll [ Skip ]
 crbug.com/842731 [ Android_One ] system_health.memory_mobile/background:news:nytimes [ Skip ]
 crbug.com/843547 [ Android_Go ] system_health.memory_mobile/background:news:nytimes [ Skip ]