Enable gfx_unittests on Fuchsia x64 bots

Bug: 952652
Change-Id: Ibab893bcd8e139fae5417fdedeb66b76a7015a07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1603262Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658306}

testing/buildbot/chromium.linux.json

@@ -1783,6 +1783,24 @@
         },
         "test": "fidlgen_js_unittests"
       },
+      {
+        "args": [
+          "--test-launcher-filter-file=../../testing/buildbot/filters/fuchsia.gfx_unittests.filter"
+        ],
+        "merge": {
+          "args": [],
+          "script": "//testing/merge_scripts/standard_gtest_merge.py"
+        },
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "dimension_sets": [
+            {
+              "kvm": "1"
+            }
+          ]
+        },
+        "test": "gfx_unittests"
+      },
       {
         "merge": {
           "args": [],

testing/buildbot/test_suite_exceptions.pyl

@@ -507,12 +507,6 @@
       },
     },
   },
-  'gfx_unittests': {
-    'remove_from': [
-      # chromium.linux
-      'Fuchsia x64',  # https://crbug.com/952652
-    ],
-  },
   'gin_unittests': {
     'remove_from': [
       # chromium.clang