v8binding: Enable Dromaeo perf on Linux

It looks that the issue is already resolved and we can enable Dromaeo
perf again.  The following pinpoint job succeeded.
https://pinpoint-dot-chromeperf.appspot.com/job/1274d41e920000

Bug: 984578
Change-Id: Icb7c3573842ac40a8764205e2803273d96c4a9e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2360055Reviewed-by: Wenbin Zhang <wenbinzhang@google.com>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798677}

tools/perf/expectations.config

@@ -86,7 +86,6 @@ crbug.com/1062104 blink_perf.shadow_dom/imperative-api-assigned-slot.html [ Skip
 crbug.com/1062104 blink_perf.shadow_dom/imperative-api-insertbefore.html [ Skip ]
 
 # Benchmark: dromaeo
-crbug.com/984578 [ linux ] dromaeo/http://dromaeo.com?dom-modify [ Skip ]
 crbug.com/1050065 [ android-pixel-2 ] dromaeo/http://dromaeo.com?dom-modify [ Skip ]
 
 # Benchmark: blink_perf.svg