Run interactive_ui_tests on Win10 bots.

Improvements in the test harness may allow these to run on Win 10
(at least, they run on my Win10 box).

BUG=699442

Change-Id: Ic884ceba23bcd634ca961326eaf53ee3b6589856
Reviewed-on: https://chromium-review.googlesource.com/774442Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517321}

testing/buildbot/chromium.fyi.json

@@ -7423,6 +7423,12 @@
         },
         "test": "installer_util_unittests"
       },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": false
+        },
+        "test": "interactive_ui_tests"
+      },
       {
         "swarming": {
           "can_use_on_swarming_builders": false

testing/buildbot/chromium.win.json

@@ -849,6 +849,13 @@
         },
         "test": "installer_util_unittests"
       },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "shards": 2
+        },
+        "test": "interactive_ui_tests"
+      },
       {
         "swarming": {
           "can_use_on_swarming_builders": true