[benchmarks] Enable imgur:2019 on Nexus6 webview

It was fixed by this cl but forgot to enable it.:
https://chromium-review.googlesource.com/c/chromium/src/+/1988355

Bug: chromium:1037905
Change-Id: I8dc0402e55fc308e957fcfcc8d2562ca96c3ff5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2072220Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744349}

tools/perf/expectations.config

@@ -390,7 +390,6 @@ crbug.com/950757 [ android-go ] v8.browsing_mobile/browse:news:cnn:2018 [ Skip ]
 crbug.com/1014655 [ android-webview ] v8.browsing_mobile/browse:social:instagram:2019 [ Skip ]
 crbug.com/1036141 [ android-webview ] v8.browsing_mobile/browse:shopping:lazada:2019 [ Skip ]
 crbug.com/1036143 [ android-pixel-2 ] v8.browsing_mobile/browse:chrome:omnibox:2019 [ Skip ]
-crbug.com/1037905 [ android-nexus-6 android-webview ] v8.browsing_mobile/browse:media:imgur:2019 [ Skip ]
 crbug.com/1039801 [ android-webview ] v8.browsing_mobile/browse:social:pinterest_infinite_scroll:2019 [ Skip ]