Add missing tests to win_chromium_x64_rel

Was a blocker on a P0 bug, http://crbug.com/380709, but not anymore.

After the tryserver split, the blacklisting doesn't trigger, so it is a no-op change. Consider it a cleanup.

R=phajdan.jr@chromium.org,stip@chromium.org
BUG=225464
TEST=git cl try -m tryserver.chromium.win -b win_chromium_x64_rel

Review URL: https://codereview.chromium.org/319983004

Cr-Commit-Position: refs/heads/master@{#288368}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288368 0039d316-1c4b-4281-b951-d872f2087c98

testing/buildbot/chromium_trybot.json

@@ -13,7 +13,6 @@
     },
     {
       "test": "browser_tests",
-      "exclude_builders": ["tryserver.chromium:win_chromium_x64_rel"],
       "swarming": {
         "can_use_on_swarming_builders": true,
         "shards": 5
@@ -69,7 +68,6 @@
     "gpu_unittests",
     {
       "test": "interactive_ui_tests",
-      "exclude_builders": ["tryserver.chromium:win_chromium_x64_rel"],
       "swarming": {
         "can_use_on_swarming_builders": true,
         "shards": 3