Revert "Disable rendering.mobile/canvas_animation_no_clear on android nexus 5x."

This reverts commit f0f19cb1.

Reason for revert: pinpoint was unable to find cause of increased flakiness.

Original change's description:
> Disable rendering.mobile/canvas_animation_no_clear on android nexus 5x.
>
> NOTRY=true
> TBR=crouleau@chromium.org
> CC=​sadrul@chromium.org,vmiura@chromium.org
> BUG=1039344
>
> Change-Id: Ib4d1567010f972ad1d58305f2d17d0430e45039f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1985677
> Reviewed-by: Stephen Nusko <nuskos@chromium.org>
> Commit-Queue: Stephen Nusko <nuskos@chromium.org>
> Auto-Submit: Stephen Nusko <nuskos@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#728567}

TBR=crouleau@chromium.org,nuskos@chromium.org
NOTRY=true
CC=sadrul@chromium.org,vmiura@chromium.org

Bug: 1039344
Change-Id: I6a215825a773b4a43b599b773c84709a9e58e09d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015102Reviewed-by: Stephen Nusko <nuskos@chromium.org>
Commit-Queue: Stephen Nusko <nuskos@chromium.org>
Auto-Submit: Stephen Nusko <nuskos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734078}

tools/perf/expectations.config

@@ -264,7 +264,6 @@ crbug.com/967809 [ android-webview ] rendering.mobile/microsoft_video_city [ Ski
 crbug.com/1017244 [ mobile ] rendering.mobile/youtube_2018 [ Skip ]
 crbug.com/1036357 [ android-nexus-5 ] rendering.mobile/idle_power_blank [ Skip ]
 crbug.com/1036357 [ android-nexus-5 ] rendering.mobile/balls_svg_animations [ Skip ]
-crbug.com/1039344 [ android-nexus-5x android-webview ] rendering.mobile/canvas_animation_no_clear [ Skip ]
 
 # Benchmark: rasterize_and_record_micro.top_25
 crbug.com/764543 rasterize_and_record_micro.top_25/file://static_top_25/wikipedia.html [ Skip ]