Revert "Disable failing brows:news:cnn on webview system_health.common"

This reverts commit 3948b2b2.

Reason for revert: root cause was fixed

Original change's description:
> Disable failing brows:news:cnn on webview system_health.common
> 
> Bug: 854683
> Change-Id: I6cd308c8eadf151051916262c1d17530e85be0c1
> TBR: charliea@chromium.org
> NOTRY: true
> Reviewed-on: https://chromium-review.googlesource.com/1108396
> Reviewed-by: Annie Sullivan <sullivan@chromium.org>
> Commit-Queue: Annie Sullivan <sullivan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#568918}

TBR=sullivan@chromium.org

Change-Id: Id6aa4dd0526a4b6fea26d825cbca8e1639eebabe
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 854683
Reviewed-on: https://chromium-review.googlesource.com/1109997Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#569230}

tools/perf/expectations.config

@@ -339,7 +339,6 @@ crbug.com/736147 [ Android_One ] system_health.common_mobile/browse:social:tumbl
 crbug.com/803461 [ Nexus_5 ] system_health.common_mobile/browse:chrome:newtab [ Skip ]
 crbug.com/842163 [ Android_One ] system_health.common_mobile/browse:social:facebook_infinite_scroll [ Skip ]
 crbug.com/842163 [ Android_One ] system_health.common_mobile/browse:social:pinterest_infinite_scroll [ Skip ]
-crbug.com/854683 [ Android_Webview ] system_health.common_mobile/browse:news:cnn [ Skip ]
 crbug.com/852840 [ Android_Webview ] system_health.common_mobile/browse:media:youtube [ Skip ]
 
 # Benchmark: system_health.memory_desktop